Fix top panel size

The power button ate up 2px. I've folded in some cleanups i came across.

mentioned in merge request !526 (closed)

added 7 commits

• e0a84a82...f74281c5 - 2 commits from branch Librem5:master
• 85be1360 - layer-surface: Add the configured width and height to debug message
• a195d566 - layer-surface: Fix indentation
• ceb8d97b - layersurface: Add a section header
• b07e32d3 - top-panel: Drop useless placeholder
• 4dfd6d09 - top-panel: Remove extra horizontal padding from power button

Compare with previous version

enabled an automatic merge when the pipeline for 4dfd6d09 succeeds

merged

the commit message should have read vertical padding but i guess hey, that's just a convention anyway.