Add support for picture-in-picture windows

[ElFitaFlores]

Add support for picture-in-picture windows. Tested in Brave, Chromium and Firefox. It has the following characteristics:

1. Floats over other windows.
2. It is present in all the Hyprland workspaces.
3. Keeps its aspect ratio when resized.
4. Removed border.
5. Removed transparency.

Before:

After:

Additional notes:

• Originally I was defining a specific size for the window but the default one is good enough and also because some browsers (i.e. Brave) store the previous size giving more flexibility to the users.

[douglascamata]

Interestingly the Vivaldi picture-in-picture feature already appeara as a floating window that stay on top of others for me. I have no special configuration for this besides the classic settings of the ozone platform to wayland.

[kennethgeerts]

If this gets merged, I think it would be a good idea to also add a rule for preserving the aspect ratio. Here's how I've got it set up for chromium:

windowrule = float, title:^(?i)picture in picture$
windowrule = noborder, title:^(?i)picture in picture$
windowrule = keepaspectratio, title:^(?i)picture in picture$
windowrule = pin, title:^(?i)picture in picture$
windowrule = noinitialfocus, title:^(?i)picture in picture$
windowrule = opacity 1.0 1.0, title:^(?i)picture in picture$

[ElFitaFlores]

Didn't change anything here, not sure why GitHub shows it as new

[ElFitaFlores]

If this gets merged, I think it would be a good idea to also add a rule for preserving the aspect ratio. Here's how I've got it set up for chromium:

windowrule = float, title:^(?i)picture in picture$
windowrule = noborder, title:^(?i)picture in picture$
windowrule = keepaspectratio, title:^(?i)picture in picture$
windowrule = pin, title:^(?i)picture in picture$
windowrule = noinitialfocus, title:^(?i)picture in picture$
windowrule = opacity 1.0 1.0, title:^(?i)picture in picture$

Thanks for the ideas @kennethgeerts, I updated the PR to include some of them. It definitely improved the quality of the implementation.

[dhh]

Great work on this! I updated it a bit, put it in the new folder, and gave you commit credit. Thanks 👌