RFR: 8343188: Investigate ways to simplify MemorySegment::ofBuffer [v6]

[Per Minborg]

> This PR proposes to improve `MemorySegment::ofBuffer` making it more amenable to inlining and generally improving performance.
> 
> Testing successfully on tier1-6

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

  Rename methods

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21764/files
  - new: https://git.openjdk.org/jdk/pull/21764/files/e6b03e8b..810feb67

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21764&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21764&range=04-05

  Stats: 39 lines in 7 files changed: 0 ins; 0 del; 39 mod
  Patch: https://git.openjdk.org/jdk/pull/21764.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21764/head:pull/21764

PR: https://git.openjdk.org/jdk/pull/21764