[vectorIntrinsics] RFR: 8266775: Add VectorLoadConst node implementation for Arm SVE [v2]

[Wang Huang]

> * add VectorLoadConst node implementation for Arm SVE by
>    * add new data in `generate_iota_indices`
>    * `sve_ld1b` these data
>   
> Thank you for your review. Any suggestion is welcome.

Wang Huang has updated the pull request incrementally with one additional commit since the last revision:

  fix cost

-------------

Changes:
  - all: https://git.openjdk.java.net/panama-vector/pull/79/files
  - new: https://git.openjdk.java.net/panama-vector/pull/79/files/b8b662dc..ad86b7a2

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=79&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=79&range=00-01

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/panama-vector/pull/79.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-vector pull/79/head:pull/79

PR: https://git.openjdk.java.net/panama-vector/pull/79