.Net Processes - Fix Serialization of Input Data (microsoft#9614)

### Motivation and Context
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Updated ability to serialize complex types here:
microsoft#9525

...but missed the remoting boundary for invoke the process. This change
addresses this final gap without altering external patterns.

### Description
<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->

Convert event to JSON when invoking `ProcessActor` from
`DaprKernelProcessContext`

### Contribution Checklist
<!-- Before submitting this PR, please make sure: -->

- [X] The code builds clean without any errors or warnings
- [X] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [X] All unit tests pass, and I have added new tests where possible
- [X] I didn't break anyone 😄

dotnet/src/Experimental/Process.Runtime.Dapr/Actors/ProcessActor.cs

@@ -94,11 +94,11 @@ public Task StartAsync(bool keepAlive)
     /// </summary>
     /// <param name="processEvent">Required. The <see cref="KernelProcessEvent"/> to start the process with.</param>
     /// <returns>A <see cref="Task"/></returns>
-    public async Task RunOnceAsync(KernelProcessEvent processEvent)
+    public async Task RunOnceAsync(string processEvent)
     {
         Verify.NotNull(processEvent, nameof(processEvent));
         IExternalEventBuffer externalEventQueue = this.ProxyFactory.CreateActorProxy<IExternalEventBuffer>(new ActorId(this.Id.GetId()), nameof(ExternalEventBufferActor));
-        await externalEventQueue.EnqueueAsync(processEvent.ToJson()).ConfigureAwait(false);
+        await externalEventQueue.EnqueueAsync(processEvent).ConfigureAwait(false);
         await this.StartAsync(keepAlive: false).ConfigureAwait(false);
         await this._processTask!.JoinAsync().ConfigureAwait(false);
     }
@@ -137,10 +137,10 @@ public async Task StopAsync()
     /// </summary>
     /// <param name="processEvent">Required. The <see cref="KernelProcessEvent"/> to start the process with.</param>
     /// <returns>A <see cref="Task"/></returns>
-    public async Task SendMessageAsync(KernelProcessEvent processEvent)
+    public async Task SendMessageAsync(string processEvent)
     {
         Verify.NotNull(processEvent, nameof(processEvent));
-        await this._externalEventChannel.Writer.WriteAsync(processEvent).ConfigureAwait(false);
+        await this._externalEventChannel.Writer.WriteAsync(processEvent.ToKernelProcessEvent()).ConfigureAwait(false);
     }
 
     /// <summary>
@@ -202,7 +202,7 @@ internal override async Task HandleMessageAsync(ProcessMessage message)
                 KernelProcessEvent nestedEvent = new() { Id = eventId, Data = message.TargetEventData };
 
                 // Run the nested process completely within a single superstep.
-                await this.RunOnceAsync(nestedEvent).ConfigureAwait(false);
+                await this.RunOnceAsync(nestedEvent.ToJson()).ConfigureAwait(false);
             }
         }
     }

dotnet/src/Experimental/Process.Runtime.Dapr/DaprKernelProcessContext.cs

@@ -5,6 +5,7 @@
 using Dapr.Actors;
 using Dapr.Actors.Client;
 using Microsoft.SemanticKernel.Process;
+using Microsoft.SemanticKernel.Process.Serialization;
 
 namespace Microsoft.SemanticKernel;
 
@@ -40,7 +41,7 @@ internal async Task StartWithEventAsync(KernelProcessEvent initialEvent)
     {
         var daprProcess = DaprProcessInfo.FromKernelProcess(this._process);
         await this._daprProcess.InitializeProcessAsync(daprProcess, null).ConfigureAwait(false);
-        await this._daprProcess.RunOnceAsync(initialEvent).ConfigureAwait(false);
+        await this._daprProcess.RunOnceAsync(initialEvent.ToJson()).ConfigureAwait(false);
     }
 
     /// <summary>
@@ -49,7 +50,7 @@ internal async Task StartWithEventAsync(KernelProcessEvent initialEvent)
     /// <param name="processEvent">The event to sent to the process.</param>
     /// <returns>A <see cref="Task"/></returns>
     public override async Task SendEventAsync(KernelProcessEvent processEvent) =>
-        await this._daprProcess.SendMessageAsync(processEvent).ConfigureAwait(false);
+        await this._daprProcess.SendMessageAsync(processEvent.ToJson()).ConfigureAwait(false);
 
     /// <summary>
     /// Stops the process.

dotnet/src/Experimental/Process.Runtime.Dapr/Interfaces/IProcess.cs

@@ -31,7 +31,7 @@ public interface IProcess : IActor, IStep
     /// </summary>
     /// <param name="processEvent">Required. The <see cref="KernelProcessEvent"/> to start the process with.</param>
     /// <returns>A <see cref="Task"/></returns>
-    Task RunOnceAsync(KernelProcessEvent processEvent);
+    Task RunOnceAsync(string processEvent);
 
     /// <summary>
     /// Stops a running process. This will cancel the process and wait for it to complete before returning.
@@ -45,7 +45,7 @@ public interface IProcess : IActor, IStep
     /// </summary>
     /// <param name="processEvent">Required. The <see cref="KernelProcessEvent"/> to start the process with.</param>
     /// <returns>A <see cref="Task"/></returns>
-    Task SendMessageAsync(KernelProcessEvent processEvent);
+    Task SendMessageAsync(string processEvent);
 
     /// <summary>
     /// Gets the process information.

dotnet/src/Experimental/Process.Runtime.Dapr/Serialization/KernelProcessEventSerializer.cs

@@ -34,11 +34,20 @@ IEnumerable<KernelProcessEvent> Deserialize()
         {
             foreach (string json in jsonEvents)
             {
-                EventContainer<KernelProcessEvent> eventContainer =
-                    JsonSerializer.Deserialize<EventContainer<KernelProcessEvent>>(json) ??
-                    throw new KernelException($"Unable to deserialize {nameof(KernelProcessEvent)} queue.");
-                yield return eventContainer.Payload with { Data = TypeInfo.ConvertValue(eventContainer.DataTypeName, eventContainer.Payload.Data) };
+                yield return json.ToKernelProcessEvent();
             }
         }
     }
+
+    /// <summary>
+    /// Deserialize a list of JSON events into a list of <see cref="KernelProcessEvent"/> objects.
+    /// </summary>
+    /// <exception cref="KernelException">If any event fails deserialization</exception>
+    public static KernelProcessEvent ToKernelProcessEvent(this string jsonEvent)
+    {
+        EventContainer<KernelProcessEvent> eventContainer =
+            JsonSerializer.Deserialize<EventContainer<KernelProcessEvent>>(jsonEvent) ??
+            throw new KernelException($"Unable to deserialize {nameof(KernelProcessEvent)} queue.");
+        return eventContainer.Payload with { Data = TypeInfo.ConvertValue(eventContainer.DataTypeName, eventContainer.Payload.Data) };
+    }
 }