go/types, types2: check that alias type arguments satisfy constraints

go/types, types2: check that alias type arguments satisfy constraints

Fixes #69576.

Change-Id: I8fc077970276977dd89fc2dd3867f2765d52e54e
Reviewed-on: https://go-review.googlesource.com/c/go/+/615275
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Tim King <taking@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>