RFR: 8305418: [Linux] Replace obsolete XIM as Input Method Editor [v2]

[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 03-09-2023 19:10:36.webm](https://github.com/openjdk/jfx/assets/30704286/2a36e9d0-59be-4092-905f-e31fabc6e2e4)

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 74 commits:

 - Rework to use process_key
 - Merge branch 'master' into new_ime
   
   # Conflicts:
   #	modules/javafx.graphics/src/main/native-glass/gtk/glass_window_ime.cpp
 - Rework to use process_key
 - Don't highlight for dead keys
 - Don't move the caret on preedit
 - Add function to return relative location of the caret (it's how it's handled on Linux).
 - Merge branch 'master' into new_ime
 - Merge branch 'master' into new_ime
 - Weird API
 - JavaFX does not currently supports surrouding
 - ... and 64 more: https://git.openjdk.org/jfx/compare/5e145cc0...7bbfa914

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Changes: https://git.openjdk.org/jfx/pull/1080/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1080&range=01
  Stats: 520 lines in 15 files changed: 122 ins; 268 del; 130 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