cmd/compile: rewrite the constant parts of the prove pass

cmd/compile: rewrite the constant parts of the prove pass

Handles a lot more cases where constant ranges can eliminate
various (mostly bounds failure) paths.

Fixes #66826
Fixes #66692
Fixes #48213
Update #57959

TODO: remove constant logic from poset code, no longer needed.

Change-Id: Id196436fcd8a0c84c7d59c04f93bd92e26a0fd7e
Reviewed-on: https://go-review.googlesource.com/c/go/+/599096
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>