Add Wayland specific exception for Firefox's secondary windows

[joao-pedro-braz]

Hello all!

This pull request aims to add a Wayland specific exception to Firefox's secondary windows, such as it's Sharing Indicator, which currently is the only exception.

Also for the record, Firefox's Sharing Indicator is a normal window under Wayland, which makes it behave counter-intuitively, if anyone wants to fix this I managed to do it through this Window Rule:

Position here is set according to my own Display as to make the indicator appear on the top-center side of the screen (With a horizontal resolution of 2560 and an indicator size of 50, 2560 / 2 - 50 = 1230)

Best Regards, João Pedro Braz