Add inline replies to notifications

[ErikReider]

Fixes: #179

Had to do a lot of tweaking in this PR due to a Notification essentially being a GtkButton with content inside of it. I replaced said GtkButton with an GtkEventBox that behaves like a button but respects children with input.

Todo:

• [x] Double check the CSS and make it more accessible (probably contrast)
• [x] Make use of KeyboardMode.ON_DEMAND to be able to focus the GtkEntry when in NotiWindow. (Can't test in Sway. Maybe just support in CC if WM only supports layershell v3?). Alt method (Works in Hyprland so I pushed a PR to Sway to fix this issue)
• [x] Test in applications (tested in Chrome in https://tests.peter.sh/notification-generator/)
• [x] Add inline-reply to notiModel to_string output
• [x] Press enter to reply

Testing:

notify-send 'Title' 'body' -A inline-reply=Text or https://tests.peter.sh/notification-generator/

Everything is done here, just need to make sure that it works as expected in Sway, https://github.com/swaywm/sway/pull/7587

[tukusejssirs]

@ErikReider, do I get it right that inline replies will work on Sway after swaywm/sway#7587 is merged? 🤔

[ErikReider]

@ErikReider, do I get it right that inline replies will work on Sway after swaywm/sway#7587 is merged? thinking

Will work now, but only in the control center. We check if the compositor supports the ON_DEMAND interactivity which is required to get keyboard focus on floating notifications which is added in that PR :)