RFR: 8305418: [Linux] Replace obsolete XIM as Input Method Editor [v26]

[Thiago Milczarek Sayao]

> This replaces obsolete XIM and uses gtk api for IME.
> Gtk uses [ibus](https://github.com/ibus/ibus)
> 
> Gtk3+ uses relative positioning (as Wayland does), so I've added a Relative positioning on `InputMethodRequest`.
> 
> [Screencast from 17-09-2023 21:59:04.webm](https://github.com/openjdk/jfx/assets/30704286/6c398e39-55a3-4420-86a2-beff07b549d3)

Thiago Milczarek Sayao has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 105 commits:

 - Remove idea file
 - Fix the case when IME filters key_press (Polish ALT Gr + C)
 - Merge branch 'master' into new_ime
 - Fix for Polish AltGR combinations
 - Remove negative checks
 - Revert idea file
 - Remove unused import
 - Fix review points
 - Merge branch 'master' into new_ime
 - Merge branch 'refs/heads/master' into new_ime
 - ... and 95 more: https://git.openjdk.org/jfx/compare/5428f267...e56588ba

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Changes: https://git.openjdk.org/jfx/pull/1080/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1080&range=25
  Stats: 500 lines in 9 files changed: 109 ins; 247 del; 144 mod
  Patch: https://git.openjdk.org/jfx/pull/1080.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1080/head:pull/1080

PR: https://git.openjdk.org/jfx/pull/1080