[vectorIntrinsics+mask] RFR: 8273159: Remove LoadVectorMaskNode/StoreVectorMaskNode

[Ningsheng Jian]

Removed the nodes and related code. Try to generate the SVE ld1b/st1b extend/narrow instructions by matching specific rules.

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Commit messages:
 - 8273159: Remove LoadVectorMaskNode/StoreVectorMaskNode

Changes: https://git.openjdk.java.net/panama-vector/pull/116/files
 Webrev: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=116&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273159
  Stats: 308 lines in 12 files changed: 29 ins; 227 del; 52 mod
  Patch: https://git.openjdk.java.net/panama-vector/pull/116.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-vector pull/116/head:pull/116

PR: https://git.openjdk.java.net/panama-vector/pull/116