Add end to end tests for arm64 to support CL 8405.

There are several instruction forms commented out at the moment
they will be addressed in CL 8405 or later followups.

Change-Id: I6eeeb810c1e03cd49bb3c881bc46a29cdb817822
Reviewed-on: https://go-review.googlesource.com/8631Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
Reviewed-by: Rob Pike <r@golang.org>