Add per-window content scaling

[dawsers]

Add a new dispatcher scaleactive that scales the content of the active window

Each window can have its contents with a different scale. This can be useful for background apps/jobs you want to control and you don't want them to take much space, pinned windows etc. You can also use it for applications that have their UI too big or too small and don't support native re-scaling.

I don't think I have covered every case yet, but I wanted to propose this initial PR so you guys tell me if there is any real interest for this before I spend more time in it. I was going to implement this in hyprscroller, but it made more sense to integrate the feature in Hyprland.

There is currently a bug that I haven't figured out: Sometimes the client renders popups to be "inside the monitor", so despite the window being visible and interactive, some popups render in what would be the non-scaled monitor extents. I can attach an image if there is any interest to help.

The change should be transparent. By default the scale is 1.0, so it shouldn't interfere with Hyprland unless changed.

To try it out, add something like this to your config:

# Scaling submap
# will switch to a submap called scaling
bind = $mainMod, period, submap, scaling
# will start a submap called "scaling"
submap = scaling
# sets repeatable binds for scaling the content of the active window
bind = , 1, scaleactive, 0.4 
bind = , 1, submap, reset
bind = , 2, scaleactive, 0.6
bind = , 2, submap, reset
bind = , 3, scaleactive, 0.8
bind = , 3, submap, reset
bind = , 4, scaleactive, 1.25
bind = , 4, submap, reset
bind = , 5, scaleactive, 1.5
bind = , 5, submap, reset
bind = , 6, scaleactive, 2.0
bind = , 6, submap, reset
bind = , 0, scaleactive, -1.0
bind = , 0, submap, reset
# use reset to go back to the global submap
bind = , escape, submap, reset
# will reset the submap, meaning end the current one and return to the global one
submap = reset

#bind = $mainMode, period, scroller:scaleactive, 0.5
bind = $mainMode, comma, scaleactive, -1

The dispatcher accepts any positive floating point number as scale. Using a negative number (-1 by convention) will reset the scale of the content of that window. The scale has the same meaning as the fractional value for the monitor: 2 would make the content 2x2 times bigger. 0.5 would make it smaller.

Thanks!