RFR: 8305418: [Linux] Replace obsolete XIM as Input Method Editor [v21]

[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 95 commits:

 - Merge branch 'refs/heads/master' into new_ime
 - Merge branch 'master' into new_ime
 - Add signals to avoid warnings
 - Merge branch 'master' into new_ime
   
   # Conflicts:
   #	modules/javafx.graphics/src/main/native-glass/gtk/GlassApplication.cpp
 - Add check for jview
 - - Fix comment path
 - - Fix double keyrelease
 - - Use a work-around to relative positioning (until wayland is not officially supported)
   - Unref pango attr list
 - Merge branch 'master' into new_ime
 - Account the case of !filtered
 - ... and 85 more: https://git.openjdk.org/jfx/compare/94aa2b68...8c152c80

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Changes: https://git.openjdk.org/jfx/pull/1080/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1080&range=20
  Stats: 448 lines in 7 files changed: 62 ins; 265 del; 121 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