Reworked the handling of async results within the resolver task

[michaelstaib]

The async result handling for IQueryable and similar types has been suboptimal, making integration with systems like CosmosDB challenging. With Hot Chocolate 14, we are standardizing the handling of incomplete queries after the resolver pipeline is executed.

Previously, we had a primitive called executables in Hot Chocolate. We are now enhancing and standardizing this primitive by coupling it with the new IResolverResultPostProcessor.

These post processors are created by an expression compiler during schema building, or, if the source generator is used, by our source generator at build time.

Fixes #7152

[codecov]

Codecov Report

Attention: Patch coverage is 37.75000% with 249 lines in your changes missing coverage. Please review.

Project coverage is 75.99%. Comparing base (e071750) to head (c264c64).

Files	Patch %	Lines
...re/src/Abstractions/DefaultEnumerableExecutable.cs	0.00%	58 Missing ⚠️
...ore/src/Abstractions/DefaultQueryableExecutable.cs	51.00%	49 Missing ⚠️
.../src/Data/Execution/MongoDbCollectionExecutable.cs	0.00%	28 Missing ⚠️
...c/Abstractions/DefaultAsyncEnumerableExecutable.cs	29.03%	22 Missing ⚠️
...re/src/Abstractions/Execution/ListPostProcessor.cs	33.33%	16 Missing ⚠️
...aven/src/Data/RavenAsyncDocumentQueryExecutable.cs	12.50%	14 Missing ⚠️
...c/HotChocolate/Core/src/Abstractions/Executable.cs	44.44%	10 Missing ⚠️
...Data/Execution/MongoDbAggregateFluentExecutable.cs	0.00%	10 Missing ⚠️
.../src/Data/Execution/MongoDbFindFluentExecutable.cs	0.00%	10 Missing ⚠️
...HotChocolate/Core/src/Abstractions/Executable~1.cs	27.27%	8 Missing ⚠️
... and 10 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7152      +/-   ##
==========================================
- Coverage   78.62%   75.99%   -2.64%     
==========================================
  Files        2390     2700     +310     
  Lines      117207   133655   +16448     
==========================================
+ Hits        92150   101566    +9416     
- Misses      25057    32089    +7032     

Flag	Coverage Δ
unittests	75.99% <37.75%> (-2.64%)	⬇️

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