RFR: 8372188: AArch64: Generate atomic match rules from M4 stencils

[Aleksey Shipilev]

Current atomic match rules are all over the place in AArch64:
 - CAE and weak CAS rules are generated with the help of `cas.m4`, and then are supposed to be copy-pasted (?) into `aarch64.ad`. I did it about 20 times when fixing [JDK-8372154](https://bugs.openjdk.org/browse/JDK-8372154), gets tedious very quickly.
 - Strong CAS and get-and-set rules are still in the same section of `aarch64.ad`, and are written by hand. Yet, those can be automatically generated from M4 stencils as well.

This PR cleans that up by moving all these rules into a separate `.ad` file, which one can cleanly re-generate by invoking `m4 aarch64_atomic_ad.m4 > aarch64_atomic.ad`. The meat of the change is `aarch64_atomic.m4`, everything else is either generated from it, or removed in favor of auto-generated code. There should be no semantic change, as I attempted to move the rules mostly verbatim, only changing non-semantic stuff like match rule names and some formats.

Testing:
 - [x] Eyeballing match rules before/after
 - [x] Linux AArch64 server fastdebug, `hotspot_compiler`
 - [x] Linux AArch64 server fastdebug, `tier1`
 - [ ] Linux AArch64 server fastdebug, `all`
 - [ ] Linux AArch64 server fastdebug, jcstress run

-------------

Commit messages:
 - More Hotspot tests do not like OptoAssembly changes
 - Some tests want specific formats + moves
 - Minor stencil touchup
 - Missed L_Acq variants
 - No more atomics in main AD
 - Fix

Changes: https://git.openjdk.org/jdk/pull/28538/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28538&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8372188
  Stats: 2349 lines in 5 files changed: 1156 ins; 1193 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/28538.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28538/head:pull/28538

PR: https://git.openjdk.org/jdk/pull/28538