* remove nord and solarized dark from AppearanceV2 component
- This component already behind the extension refresh feature flag
* update the users theme to system when nord or solarized dark is selected
* For desktop, still allow all theme types by overriding the default theme service.
* change theme on the fly rather than updating local state.
- When the feature flag is removed then a migration will have to take place
We currently use a callback syntax for abstract services. This syntax isn't completely strict compliant and will fail the strictPropertyInitialization check. We also currently don't get any compile time errors if we forget to implement a function.
To that end this PR updates all platform owned services to use the appropriate abstract keyword for non implemented functions. I also updated the fields to be actual functions and not properties.
