RFR: 8310994: Add JFR event for selection operations [v2]

[Tim Prinzing]

> Added mirror event with static methods: jdk.internal.event.SelectionEvent that provides the duration of select calls and the count of how many keys are available.
> 
> Emit the event from SelectorImpl::lockAndDoSelect
> 
> Test at jdk.jfr.event.io.TestSelectionEvents

Tim Prinzing has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 12 additional commits since the last revision:

 - Change event generation:
   
   - selectNow is filtered out
   - select that times out is always sent
   - select without timeout uses duration test
 - rename event to SelectorSelect, field to selectionKeyCount.
 - Merge branch 'master' into JDK-8310994
 - remove trailing whitespace
 - event logic outside of the lock, selector in try block
 - remove unused import
 - fix TestConfigure failure
 - add event defaults
 - Merge branch 'master' into JDK-8310994
 - minor test cleanup
 - ... and 2 more: https://git.openjdk.org/jdk/compare/a4905c7c...2f7dafd8

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/16710/files
  - new: https://git.openjdk.org/jdk/pull/16710/files/fbb93112..2f7dafd8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16710&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16710&range=00-01

  Stats: 73918 lines in 2175 files changed: 42613 ins; 21404 del; 9901 mod
  Patch: https://git.openjdk.org/jdk/pull/16710.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16710/head:pull/16710

PR: https://git.openjdk.org/jdk/pull/16710