RFR: 8345125: Aarch64: Add aarch64 backend for Float16 scalar operations [v3]

[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 with a new target base due to a merge or a rebase. The pull request now contains four commits:

 - Addressed review comments
 - Merge master
 - Address review comments
 - 8345125: Aarch64: Add aarch64 backend for Float16 operations
   
   This patch adds aarch64 backend for scalar FP16 operations namely - add,
   subtract, multiply, divide, fma, sqrt, min and max.

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Changes: https://git.openjdk.org/jdk/pull/23748/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23748&range=02
  Stats: 530 lines in 14 files changed: 344 ins; 2 del; 184 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