Merge branch 'broadway-modal-hint' into 'main'

[GTK4] gdk/broadway: Implements modal hint for Broadway surface

See merge request GNOME/gtk!4428

diff --cc gdk/broadway/broadway-protocol.h
Simple merge

diff --cc gdk/broadway/broadway-server.c
Simple merge

diff --cc gdk/broadway/broadwayd.c
Simple merge

diff --cc gdk/broadway/gdkbroadway-server.c
Simple merge

diff --cc gdk/broadway/gdkeventsource.c
Simple merge

diff --cc gdk/broadway/gdksurface-broadway.c
Simple merge