Wayland: apply cursor settings immediately

[stefonarch]

Just noticed that both on niri and labwc the cursor theme and size are applied on reloading the config; on labwc labwc -r is enough while on niri just niri msg action load-config-file is not working, but changing any value reloads the cursor theme too (as it gets hot-reloaded).

So we could reload configs for compositor running, at least for labwc. Need to test all others... as not all read well our setting afaik.

Hyprland, Wayfire and sway need session restart, I see.