Generic interceptors

[RikkiGibson]

Test plan: #67421
Continuation of #68218

Addresses point 1 in #68218 (comment)

We want to deliver a critical level of generics support in .NET 8. Namely, in addition to permitting interceptors with arity 0, we will also permit interceptors whose arity equals the net arity of the original method (sum of arity of containing types plus arity of original method). The type arguments from the original method and containing types are passed along to the interceptor in source order, i.e. starting from the outermost generic type, and inwards to the original method.

It might also be worthwhile to spend a little more time investigating the "unification" approach. But it's something that could be added later without breaking things.

[cston]

Consider using the existing extension method, and also use TypeWithAnnotations since that type is used for Construct().

var builder = ArrayBuilder<TypeWithAnnotations>.GetInstance();
method.ContainingType.GetAllTypeArgumentsNoUseSiteDiagnostics(builder);
builder.AddRange(method.TypeArgumentsWithAnnotations);
interceptor = interceptor.Construct(builder.ToImmutableAndFree());
``` #Resolved

[RikkiGibson]

@jcouv Please take a look when you get the chance.

[jcouv]

Done with review pass (iteration 2)

[jcouv]

Looks like a comma is missing here

[jcouv]

LGTM Thanks (iteration 7) modulo missing comma