This commit changes the way icons are displayed on the bar.
There was an issue with how app icons were sized using shrink_to_fit.
This has been changed to use fit_to_exact_size instead, relying on the
font size as a starting point and scaling it to 1.4 of its size, making
the icons to appear larger.
The same scaling was done to all the widget icons as well to make them
look unified.
The visual changes include:
* the focused_window section is now indicating the active window in a stack and has hover effect.
* custom icons for all the layouts, including `paused`, `floating`, `monocle` states.
* custom layout/state picker with configurable options.
* display format configuration for the layouts (Icon/Text/IconAndText)
* display format configuration for the focused_window section (Icon/Text/IconAndText)
* display format configuration for the workspaces section (Icon/Text/IconAndText)
Csaba