[API Proposal] Linq-like APIs for analyzers

[alrz]

This was implemented for generators but never ported back to analyzers. This could make analyzers more terser than they currently are.

Usage Examples

For example if we want to warn if a type argument is not marked with [SomeAttribute] when the type parameter is marked as [SomeAttribute] as some sort of generic constraint.

// uncomment to resolve
// [SomeAttribute]
class C;

void M<[SomeAttribute] T>(T arg);

M(new C()); // warning with a fixer

context.OperationProvider
  .OfType<IInvocationOperation>()
  .Where( /* method is generic */ )
  .SelectMany( /* return type arg, type parameter pairs */ )
  .Where( /* type parameter is marked with the attribute */ )
  .Where(  /* type arg is not marked with the attribute */)
  .Report("type is not marked with the attribute")
  .Fix("add the attribute to the type", context => /* add the attribute to the type */);