Parse compound and special names in the macro role attributes
(`@freestanding` and `@attached`). This allows both compound names and
initializers, e.g., `init(coding:)`.
Fixes rdar://107967344.
SE-0382 allows macro parameters to have default arguments. Enable these
default arguments, with the normal type checking rules. One
significant quirk to this implementation is that the actual default
argument values don't make it to the macro implementation. This is a
previously-unconsidered design problem we'll need to address.
Tracked by rdar://104043987.
Check accessibility of all build{Partial}Block overloads and
diagnose if none of them are as accessible as type, otherwise
swift interfaces could end up with invalid result builder
declarations when type is public and all builder methods are
internal.
Resolves: rdar://104384604
