go/types: add additional test data from types2

Add some test data files that were not included in go/types.

- Issue 43125 only pertained to types2 because go/ast differentiates
  StarExpr, UnaryExpr, and BinaryExpr, so typexpr.go was already
  catching the invalid type expressions.
- Issues 42987 and 43190 are handled differently by go/parser.
- main.go2 was not added when ported to go/types, because this work
  happened on the dev.regabi branch, which didn't support generics.

Test files are modified to adjust errors messages and positions, and to
update the copyright year.

Change-Id: Ia737eaab9afb2b59600b661ccf3eec3cbbb2d66c
Reviewed-on: https://go-review.googlesource.com/c/go/+/315070


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>