RFR: JDK-8300582: Introduce interface for unaligned memory accesses [v11]

[Justin King]

> Introduce interface for unaligned memory accesses `UnalignedAccess`, consolidate the byte swapping implementation to `byteswap`, and switch to a generic implementation of `Bytes`.

Justin King has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains one commit:

  Propose unaligned access interface
  
  Signed-off-by: Justin King <jcking at google.com>

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Changes: https://git.openjdk.org/jdk/pull/12078/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12078&range=10
  Stats: 319 lines in 2 files changed: 319 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/12078.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12078/head:pull/12078

PR: https://git.openjdk.org/jdk/pull/12078