Actually add a whole new panel for symbol editor appearance control.
Use the SYMBOL_EDITOR_SETTINGS as the source of truth in a
couple more places, but the SCH_PAINTER settings are still
driving quite a bit here and there.
Fixes: https://gitlab.com/kicad/code/kicad/-/issues/18830
Remove some useless spacers, and do not force some widgets to have a to
large size (by removing empty areas).
Work in progress: one panel is still too big.
