* "description" for override completion is now annotatable
* "description" doesn't include attributes and decl introducer, but it
includes generic paramters, effects specifiers, result type clause,
and generic where clauses
* "name" now only include the name and the parameter names
* "sourcetext" should be the same
rdar://63835352
* If "required" or "convenience" is specified, emit only initializers
* If "final" or "open" is specified, don't emit initializers or typealias
* If "typealias" is specified, emit only associated type implementation
* Emit "override" or "required" modifier for initializers
* Emit access modifier for initializers
* Emit designated initializers even if "override" is specified
* Don't emit inheritance clause for associated type implentation
