Support demangling bound generic types (e.g., Array<Int>) and forming
type metadata for them. For now, only support non-nested generic types
with up to three generic parameters.
Extend the protocol descriptor with a (space-separated) list of associated
type names, in the order of their requirements. Use this information in
the runtime to support lookup of associated type witnesses by name when
mapping a mangled name to a type and substituting generic parameters.
Extend _typeByMangledName with support for user-provided type parameter
substitutions, where type parameters that occur in the mangling can be
replaced with specific types.
Search through the new section containing Swift protocol descriptor
references to resolve protocols by mangled name. Use this
functionality to support protocol composition types within
_typeForMangledName.
Introduce a standard library/runtime entry point that produces type metadata
given a mangled name, based on the TypeDecoder logic lifted from the remote
mirrors library.
Implement support for tuple types as a proof-of-concept.
