RFR: 8318678: Vector access on heap MemorySegments only works for byte[] [v2]

[Per Minborg]

> This PR proposes removing the restriction that only heap `MemorySegment` wrapping a `byte` array can be accessed by Vectors. Now any array type can be used provided the element alignment constraints are respected.

Per Minborg has updated the pull request incrementally with one additional commit since the last revision:

  Allow unaligned array access

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16360/files
  - new: https://git.openjdk.org/jdk/pull/16360/files/75bd88ca..4828a98b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16360&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16360&range=00-01

  Stats: 326 lines in 41 files changed: 137 ins; 99 del; 90 mod
  Patch: https://git.openjdk.org/jdk/pull/16360.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16360/head:pull/16360

PR: https://git.openjdk.org/jdk/pull/16360