RFR: 8365611: Throttle any JFR event [v2]

[Thomas Stuefe]

> This patch prepares the way to throttle any JFR event, not only the three events for which we hard-code throttlers. It also cleans up the throttler code and replaces the switch construct with a lookup table.
> 
> The patch does not yet enable throttling for any other event, since that may be a contentious move, and I would like for this patch to go in without too much fuss. So I did not make any new events "throttleble".
> 
> If it turns out to be non-contentious, I am fine with just enabling throttling capability for all events.

Thomas Stuefe has updated the pull request incrementally with one additional commit since the last revision:

  Markus Feedback

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Changes:
  - all: https://git.openjdk.org/jdk/pull/26801/files
  - new: https://git.openjdk.org/jdk/pull/26801/files/34c340fb..3cb74305

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26801&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26801&range=00-01

  Stats: 9 lines in 2 files changed: 4 ins; 4 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/26801.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26801/head:pull/26801

PR: https://git.openjdk.org/jdk/pull/26801