[dev.regabi] go/types: add support for language version checking

This is a port of CL 289509 to go/types. It differs from that CL in
codes added to errors, to fit the new factoring of check_test.go, and to
allow go/types to import regexp in deps_test.go

For #31793

Change-Id: Ia9e4c7f5aac1493001189184227c2ebc79a76e77
Reviewed-on: https://go-review.googlesource.com/c/go/+/291317


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>