Add CancellationToken overloads to Compile methods

[daviddotcs]

Since CSharpCompilation.Emit and CSharpSyntaxTree.Parse support cancellation, it'd be good to be able to forward cancellation tokens down to those potentially long-running methods. Ideally they'd have been optional parameters added to each of the compile methods, however that would be a breaking change to the API so I've added them as overloads.

[daviddotcs]

I inadvertently made a bigger breaking change (where any overrides of RazorEngine.CreateAndCompileToStream(string, RazorEngineCompilationOptions) would no longer be called) by trying to avoid breaking changes to the API, so I've reverted back to proposing the Compile and CompileAsync methods have an optional CancellationToken parameter added, and the CreateAndCompileToStream has a non-optional CancellationToken parameter added.

[adoconnection]

Hi 👋 thanks for pull request. Do we really need cancellation token in non async methods?

[daviddotcs]

Hi. Yes, I believe both the asynchronous and synchronous methods would benefit from being cancellable. The CSharpCompilation.Emit and CSharpSyntaxTree.Parse methods are both synchronous and support cancellation, for example.

I did a brief bit of searching on the matter and didn't find too much, but in https://learn.microsoft.com/en-us/dotnet/standard/threading/cancellation-in-managed-threads it makes the following statement which suggests that supporting cancellation tokens in synchronous methods is valid:

Starting with .NET Framework 4, .NET uses a unified model for cooperative cancellation of asynchronous or long-running synchronous operations.

[adoconnection]

released in 2023.11.1 🚀
https://www.nuget.org/packages/RazorEngineCore/