RFR: 8368478: RichTextArea: add IME support [v2]

[Andy Goryachev]

> Adds Input Method Editor (IME) support to `RichTextArea`/`CodeArea`.
> 
> Tested on macOS and Windows 11 with Japanese and Chinese (pinyin) input methods.
> Please test this on Linux, even though there is no platform-specific code in this PR (should work the same way it does in `TextArea`/`TextField`)
> 
> For testing, one can use the updated Monkey Tester
> https://github.com/andy-goryachev-oracle/MonkeyTest
> (optionally enable IME events in stdout with Logging -> IME Monitor)

Andy Goryachev 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 11 additional commits since the last revision:

 - review comments
 - Merge branch 'master' into 8368478.ime
 - test
 - accessor
 - cleanup
 - whitespace
 - Merge remote-tracking branch 'origin/master' into 8368478.ime
 - ime object
 - ime location
 - ime works
 - ... and 1 more: https://git.openjdk.org/jfx/compare/19d028f3...3bb8d850

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/1938/files
  - new: https://git.openjdk.org/jfx/pull/1938/files/d269071b..3bb8d850

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1938&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1938&range=00-01

  Stats: 348 lines in 12 files changed: 179 ins; 36 del; 133 mod
  Patch: https://git.openjdk.org/jfx/pull/1938.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1938/head:pull/1938

PR: https://git.openjdk.org/jfx/pull/1938