RFR: 8345125: Aarch64: Add aarch64 backend for Float16 scalar operations [v2]

[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:

  Address review comments

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Changes:
  - all: https://git.openjdk.org/jdk/pull/23748/files
  - new: https://git.openjdk.org/jdk/pull/23748/files/a608a035..4d699740

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23748&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23748&range=00-01

  Stats: 7 lines in 1 file changed: 0 ins; 0 del; 7 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