[dev.typeparams] go/types: factor out constraint satisfaction check
This is a port of CL 322070 to go/types, adjusted for the different
error reporting API.
Change-Id: I75eafe015b5b00554116527ea021e7a5f9e0343b
Reviewed-on: https://go-review.googlesource.com/c/go/+/324759
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>