[dev.typeparams] go/types: update TypeParam APIs to match types2
This is a partial port of CL 323029, consisting only of changes to
go/types. Changes to the importer will be made in a separate CL.
Change-Id: I3b300f5e8f4df36c2c87e3f164705cd3c36218ac
Reviewed-on: https://go-review.googlesource.com/c/go/+/335145
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>