go/types, types2: move exported predicates into separate file
This allows those functions to be generated for go/types.
Also, change the generator's renameIdent mechanism so that
it can rename multiple identifiers in one pass through the
AST instead of requiring multiple passes.
No type-checker functionality changes.
Change-Id: Ic78d899c6004b6a0692a95902fdc13f8ffb47824
Reviewed-on: https://go-review.googlesource.com/c/go/+/542757
Run-TryBot: Robert Griesemer <gri@google.com> Reviewed-by: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>