AdwDialog

TODO:

• ::close-request replacement
  • reimplement close response in alert dialog
• swipes
• ::close-request on Adw(Application)Window - apps should be able to use it without breaking dialogs
• rename AdwMessageDialog2
• make AdwBottomSheet private for now
• Make adw_dialog_present() less painful to use
• future proofing the API
  • flags for adw_dialog_present() for per-tab dialogs
  • widget if we want to animate from one (not necessary, can be a separate func probably)
• docs for new API
  • adapt docs for renamed widgets
• tests
• share dialog code between AdwWindow and AdwApplicationWindow
• global esc to close
• split remove_breakpoint() into a separate MR
• finish cleaning up the commits
• review default sizes
• update copyright lines