RFR: 8345125: Aarch64: Add aarch64 backend for Float16 scalar operations [v4]

[Bhavana Kilambi]

> This patch adds aarch64 backend for scalar FP16 operations namely - add, subtract, multiply, divide, fma, sqrt, min and max.

Bhavana Kilambi has updated the pull request incrementally with one additional commit since the last revision:

  Update asmtest.out.h to keep it consistent with aarch64-asmtest.py

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/23748/files
  - new: https://git.openjdk.org/jdk/pull/23748/files/eb667fc6..6a49a11d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23748&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23748&range=02-03

  Stats: 577 lines in 1 file changed: 7 ins; 3 del; 567 mod
  Patch: https://git.openjdk.org/jdk/pull/23748.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23748/head:pull/23748

PR: https://git.openjdk.org/jdk/pull/23748