[dev.typeparams] go/types: report better error for invalid untyped operation

This is port of CL 328053 for types2 to go/type.

The change is identical, but for some tweaks to the error positions in
tests.

Updates #46749

Change-Id: I8d34c5b1669e59e4ec7d91f81dcf655b2bfd89a5
Reviewed-on: https://go-review.googlesource.com/c/go/+/328869


Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>