RFR: 8330821: Rename UnsafeCopyMemory [v2]

[Scott Gibbons]

> Renaming UnsafeCopyMemory to UnsafeMemoryAccess since this class is now being used for Unsafe::setMemory.  This is a pure rename only.

Scott Gibbons has updated the pull request incrementally with one additional commit since the last revision:

  Address review comment

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18889/files
  - new: https://git.openjdk.org/jdk/pull/18889/files/281a1da9..aaa3d416

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18889&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18889&range=00-01

  Stats: 67 lines in 6 files changed: 0 ins; 0 del; 67 mod
  Patch: https://git.openjdk.org/jdk/pull/18889.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18889/head:pull/18889

PR: https://git.openjdk.org/jdk/pull/18889