RFR: 8258953: AArch64: move NEON instructions to aarch64_neon.ad

[Dong Bo]

As discussed in [1], all NEON instructions should be moved from `aarch64.ad` to `aarch64_neon.ad`.

In the first commit [2] of this PR, the NEON instructions are deleted from `aarch64.ad` and appended to `aarch64_neon.ad`.
I compared the generated code in `aarch64_neon.ad` with original code in `aarch64.ad`, no suspicious differences found.
The last two commits just simply move code around in `aarch64_neon.ad` to put related instructions together, i.e. `LoadStore` [3], `Reduction` [4].

This also supports vector length 4 for `vsraa8B_imm` and `vsrla8B_imm`, vector length 2 for `vsraa4S_imm` and `vsrla4S_imm`, fixes few typos, e.g. `vor8B`, `vsrla4S_imm`.

[1] https://github.com/openjdk/jdk/pull/1215#issuecomment-728186803
[2] https://github.com/dgbo/jdk/commit/40cbe99e647cdf93712edf8f77ab3b5b30ea0a95
[3] https://github.com/dgbo/jdk/commit/695fb8f8ef009b733a8f804e791347f4bfe2572e
[4] https://github.com/dgbo/jdk/commit/e0c38aa9aaa6af9925a3821328384b1e2b2c2070

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

Commit messages:
 - put all VReduction together
 - put all VLoadStore together
 - 8258953: AArch64: move NEON instructions to aarch64_neon.ad

Changes: https://git.openjdk.java.net/jdk/pull/2273/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2273&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258953
  Stats: 5703 lines in 3 files changed: 3241 ins; 2442 del; 20 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2273.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2273/head:pull/2273

PR: https://git.openjdk.java.net/jdk/pull/2273