Support for .NET CancellationTokens

[koenbeuk]

This PR allows for grain methods to be cancelled using a CancellationToken. The implementation is loosely based on the existing GrainCancellationToken support that is already available.

1. CodeGen detects the use of a CancellationToken in a grain interface method
2. If multiple CancellationTokens are used within the same grain interface method then ORLEANS0109 diagnostic is raised
3. The generated proxy throws early if cancellation is requested. Otherwise it will register for cancellation and sends a one-way message to ICancellableInvokableGrainExtension.CancelRemoteToken to mark this token as canceled
4. CancellableInvokableGrainExtension looks up the grains ICancellationRuntime component to mark the token as canceled
5. The generated invokable implements an additional interface: ICancellableInvokable which exposes the method: GetCancellableTokenId
6. Each instance of a CancellableInvokable sets a cancellableTokenId as Guid.NewGuid()
7. The InvokeInner implementation on the invokable can optionally interact with an ICancellationRuntime to track cancellation of this invokable.

Once the invokable completes, its CancellationTokenSource obtained through the ICancellationRuntime is always Canceled

Fixes: #8958

Microsoft Reviewers: Open in CodeFlow

[koenbeuk]

There is a regression with supporting IAsyncEnumerable with this PR. Will fix that regression and in turn, try and fix #8958