RFR: 8342677: Add IR validation tests for newly added saturated vector add / sub operations [v2]

[Jatin Bhateja]

> This is a follow up PR to https://github.com/openjdk/jdk/pull/20507
> It adds IR validation tests for newly added saturated vector add / sub operations.

Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:

  Review resolutions

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21603/files
  - new: https://git.openjdk.org/jdk/pull/21603/files/400ffe45..61ce8866

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21603&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21603&range=00-01

  Stats: 137 lines in 2 files changed: 84 ins; 11 del; 42 mod
  Patch: https://git.openjdk.org/jdk/pull/21603.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21603/head:pull/21603

PR: https://git.openjdk.org/jdk/pull/21603