RFR: 8305418: [Linux] Replace obsolete XIM as Input Method Editor [v31]

[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 114 commits:

 - Merge branch 'master' into new_ime
 - Set IBUS_ENABLE_SYNC_MODE=1
 - Revert "Set IBUS_ENABLE_SYNC_MODE=1"
   
   This reverts commit 8eccd9866b1e9931356557463997ccf53673fbfa.
 - Set IBUS_ENABLE_SYNC_MODE=1
 - Merge branch 'master' into new_ime
 - Merge branch 'master' into new_ime
 - Revert "Fix for Polish AltGR combinations"
   
   This reverts commit 78e27e9deba2eda96b86186692da4f8dc2a3a1ff.
 - Revert "Fix the case when IME filters key_press (Polish ALT Gr + C)"
   
   This reverts commit 112ed6f4306a42378255c858306f9625ea2b5fa8.
 - Revert "Remove idea file"
   
   This reverts commit e56588baad42c07a5b872d27603a97e06be97649.
 - Remove idea file
 - ... and 104 more: https://git.openjdk.org/jfx/compare/67eed6d8...16b3eebe

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Changes: https://git.openjdk.org/jfx/pull/1080/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1080&range=30
  Stats: 454 lines in 7 files changed: 68 ins; 269 del; 117 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