cmd/go: add IgnoredOtherFiles to go list; pass IgnoredFiles to vet

Show constraint-ignored non-.go files in go list, as Package.IgnoredOtherFiles
(same as go/build's IgnoredOtherFiles).

Pass full list of ignored files to vet, to help buildtag checker.

For #41184.

Change-Id: I749868de9082cbbc1efbc59370783c8c82fe735f
Reviewed-on: https://go-review.googlesource.com/c/go/+/240553


Trust: Russ Cox <rsc@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>