RFR: 8330821: Rename UnsafeCopyMemory [v3]

[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:

  Missed a couple

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18889/files
  - new: https://git.openjdk.org/jdk/pull/18889/files/aaa3d416..e8b86eee

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18889&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18889&range=01-02

  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 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