RFR: 8259948: Aarch64: Add cast nodes for Aarch64 Neon backend [v7]

[Wang Huang]

> * In this issue, we plan to complete all missing implementation for aarch64 neon backend. For example, cast from Byte to Long, cast from Long to Byte, and so on.
> * It may be a solver of JDK-8269866, or part of it.

Wang Huang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:

 - merge master & fix conflict
 - code refine
 - fix bugs
 - fix codes
 - fix codes
 - fix code style
 - fix bugs
 - 8259948: Aarch64: Add cast nodes for Aarch64 Neon backend

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Changes: https://git.openjdk.java.net/jdk/pull/4839/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4839&range=06
  Stats: 521 lines in 6 files changed: 273 ins; 54 del; 194 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4839.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4839/head:pull/4839

PR: https://git.openjdk.java.net/jdk/pull/4839