Support credential-less fileshare datastore (#36392)

* support credential less file datastore via sdk/cli

* update changelog

* update docstring

sdk/ml/azure-ai-ml/CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Bugs Fixed
 - Workspace update no longer broken for older workspaces due to deprecated tags.
+- Support credential-less fileshare datastore
 
 ## 1.18.0 (2024-07-09)
 

sdk/ml/azure-ai-ml/azure/ai/ml/_schema/_datastore/azure_storage.py

@@ -42,8 +42,8 @@ class AzureFileSchema(AzureStorageSchema):
         [
             NestedField(AccountKeySchema),
             NestedField(SasTokenSchema),
-        ],
-        required=True,
+            NestedField(NoneCredentialsSchema),
+        ]
     )
 
     @post_load

sdk/ml/azure-ai-ml/azure/ai/ml/entities/_datastore/azure_storage.py

@@ -49,7 +49,7 @@ class AzureFileDatastore(Datastore):
     :type protocol: str
     :param properties: The asset property dictionary.
     :type properties: dict[str, str]
-    :param credentials: Credentials to use for Azure ML workspace to connect to the storage.
+    :param credentials: Credentials to use for Azure ML workspace to connect to the storage. Defaults to None.
     :type credentials: Union[~azure.ai.ml.entities.AccountKeyConfiguration,
         ~azure.ai.ml.entities.SasTokenConfiguration]
     :param kwargs: A dictionary of additional configuration parameters.
@@ -67,7 +67,7 @@ def __init__(
         endpoint: str = _get_storage_endpoint_from_metadata(),
         protocol: str = HTTPS,
         properties: Optional[Dict] = None,
-        credentials: Union[AccountKeyConfiguration, SasTokenConfiguration],
+        credentials: Optional[Union[AccountKeyConfiguration, SasTokenConfiguration]] = None,
         **kwargs: Any
     ):
         kwargs[TYPE] = DatastoreType.AZURE_FILE