[vectorIntrinsics+fp16] RFR: 8295992: Add support for iotaShuffle and addIndex APIs for Halffloat vector type.

[Swati Sharma]

Hi All,

The patch contains the below changes:
- Java vector API changes to support iotaShuffle and addIndex operations for Halffloat vectors.
- Re enable generation of test points for these APIs in vector API test automation script.

Please review and provide your feedback.

Thanks,
Swati

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Commit messages:
 - 8295992: Add support for iotaShuffle and addIndex APIs for Halffloat vector type.

Changes: https://git.openjdk.org/panama-vector/pull/207/files
 Webrev: https://webrevs.openjdk.org/?repo=panama-vector&pr=207&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295992
  Stats: 468 lines in 18 files changed: 376 ins; 48 del; 44 mod
  Patch: https://git.openjdk.org/panama-vector/pull/207.diff
  Fetch: git fetch https://git.openjdk.org/panama-vector pull/207/head:pull/207

PR: https://git.openjdk.org/panama-vector/pull/207