cmd/compile/internal/types2: report types for mismatched call and return statements

cmd/compile/internal/types2: report types for mismatched call and return statements

Thanks to emmanuel@orijtech.com who wrote the initial version of
this change (CL 354490).

This change is following CL 354490 in idea but also contains various
simplifications, slightly improved printing of signature/type patterns,
adjustments for types2, and some fine-tuning of error positions.

Also adjusted several ERROR regexp patterns.

Fixes #48834.
Fixes #48835.

Change-Id: I31cf20c81753b1dc84836dbe83a39030ceb9db23
Reviewed-on: https://go-review.googlesource.com/c/go/+/364874
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>