[vectorIntrinsics] RFR: 8266286: Add LoadVectorGather and StoreVectorScatter's partial version [v2]

[Wang Huang]

> * Add LoadVectorGather and StoreVectorScatter's partial version
> *  use `sve_whilelo`

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

  fix style

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Changes:
  - all: https://git.openjdk.java.net/panama-vector/pull/88/files
  - new: https://git.openjdk.java.net/panama-vector/pull/88/files/dd909962..4f0c1273

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=88&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=88&range=00-01

  Stats: 154 lines in 2 files changed: 66 ins; 64 del; 24 mod
  Patch: https://git.openjdk.java.net/panama-vector/pull/88.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-vector pull/88/head:pull/88

PR: https://git.openjdk.java.net/panama-vector/pull/88