RFR: 8342818: Implement CPU Time Profiling for JFR [v10]

[Johannes Bechberger]

> This is the code for the [JEP draft: CPU Time based profiling for JFR].

Johannes Bechberger has updated the pull request incrementally with two additional commits since the last revision:

 - Only do timer init and removal at global safepoint
 - Only do timer init and removal at global safepoint

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20752/files
  - new: https://git.openjdk.org/jdk/pull/20752/files/814bb97b..18a83be7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20752&range=09
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20752&range=08-09

  Stats: 72 lines in 4 files changed: 45 ins; 15 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/20752.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20752/head:pull/20752

PR: https://git.openjdk.org/jdk/pull/20752