Support Attach Modal Dialogs Gnome setting

[jtaala]

Related to #902.

Due to some (previously observed) complexities with PaperWM's tiling/window-manage model, Gnome's "Attach Modal Dialogs" mode for windows is not currently compatible with PaperWM.

As such, this Gnome setting is a managed setting in PaperWM: https://github.com/paperwm/PaperWM?tab=readme-ov-file#recommended-gnome-shell-settings

This request is to add specific support for this Gnome windowing option.

[jtaala]

Some notes from previously observed behaviour with "Attach Modal Dialogs":

• comment out this line to stop PaperWM managing (and disabling) this Gnome setting:
  

  PaperWM/patches.js

  Line 528 in a3bbdc1

  saveRuntimeDisable(mutterSettings, 'attach-modal-dialogs', false);

• we should be able to identify a modal dialog (metaWindow) with something like

metaWindow.get_window_type() === Meta.WindowType.MODAL_DIALOG

• I think we'd need specific logic to manage the placement (and moving with parent) within our tiling model.

[Lythenas]

I briefly tried out the Attach Modal Dialogs setting and the main issue I encountered is that when a window moves out of the screen the dialog will move to the next monitor. I don't know if there are other issues, but that might be manageable by paperwm (e.g. hide or clip the dialog if the parent is outside of the monitor).

[jtaala]

Thanks @Lythenas. I also noticed that notice a model "dialog" moves the parent window instead, with the modal dialog staying in it's original position, until I release a button (then it snaps to the parent window) - which looks very strange.