[dev.simd] cmd/compile, simd: add AES instructions

[dev.simd] cmd/compile, simd: add AES instructions

AVXAES is a composite feature set, Intel did listed it as "AVXAES" in
the XED data instead of separating them.

The tests will be in the next CL.

Change-Id: I89c97261f2228b2fdafb48f63e82ef6239bdd5ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/706055
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>