Intercept ValueTask and ValueTask<T>

[hivanov]

The types ValueTask and ValueTask<T> are not intercepted with the async interceptor, always going through the InterceptSynchronous method.

[hivanov]

Update: it seems that ValueTask and ValueTask<T> methods are forced to completion, and thus go through InterceptSynchronous. Maybe that's the reason why we've got this discrepancy.

[JSkimming]

@hivanov

The discrepancy is because this library does not consider ValueTask and ValueTask<T> (it predates them by a few years) and it determines whether a method is asynchronous based on it returning Task or Task<T>.

PRs are always welcome. Almost all the secret source is in the class AsyncDeterminationInterceptor, that's where you should start looking if you want support for ValueTask and ValueTask<T>.