Draft: Port to GTK 4
Port Phosh from GTK 3 (and GTK 3 based dependencies like Handy) to GTK 4 (and GTK 4 based equivalents like Adwaita).
This MR is far from complete and untested, but I wanted to open it so we can discuss the changes in one common place.
CC: @suraj_sloth @gautham_x as we planned on doing this together.
Edited by Arun Mani J