RFR: 8355585: Aarch64: Add aarch64 backend for Float16 vector operations

[Bhavana Kilambi]

This patch adds aarch64 backend (both Neon and SVE) for FP16 vector operations - add, mul, sub, div, min, max, sqrt and fma.

Testing:
JTREG tests - hotspot_all, jdk (tier 1-3) and langtools (tier 1) pass on aarch64 which also includes the JTREG test to test the FP16 vector operations - `test/hotspot/jtreg/compiler/vectorization/TestFloat16VectorOperations.java`

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Commit messages:
 - 8355585: Aarch64: Add aarch64 backend for Float16 vector operations

Changes: https://git.openjdk.org/jdk/pull/25096/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25096&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8355585
  Stats: 1198 lines in 8 files changed: 495 ins; 0 del; 703 mod
  Patch: https://git.openjdk.org/jdk/pull/25096.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25096/head:pull/25096

PR: https://git.openjdk.org/jdk/pull/25096