Another stepping stone for settings sync, should enable easier debug for us and manual sync solution for the impatient. Also should make wiping localstorage less of a problem since it also backs up user highlights which don't have proper UI for them.
Major:
Changed ImportExport component into a service since it's mostly logic/direct DOM-manip, not much of markup going on, makes it more reusable and avoid mess with slots
Implemented settings save/restore function
New dropdown button in modal footer: save, save with theme, restore
Settings saved with array version - current version [1, 0] - works similarly to semver but in array, for future-proofing it will refuse to load settings with major version != 1 (i.e. [2, 0]) but will work different minor version, i.e. [1, 1].
Separate control for theme saving since theme data is quite heavy.
For future we might add dialog box asking if user wants to import theme as well if it's present
Restoring goes over supported properties and updates them using setOption with data found in file.
Minor stuff:
one more fix for "p's broken theme" fucking up theme editor and making it mostly unusable
changed "Peek"/"Close" buttons to use icons instead, feels a bit more natural and less confusing given that there are now button in footer too.
panel footers no longer use panel header colors, it just looked silly and didn't really work with some themes (redmond), cleaned up their styles a bit
