Manifest V3

[Maluen]

The extension should be ported from current MV2 to MV3. Deadline is January 2023, after which Chrome will stop running MV2 extensions, or at least prevent new installations and updates.

See https://developer.chrome.com/docs/extensions/mv3/intro/

The current chrome MV3 implementation is still bugged in some areas and some other APIs might change, so it's probably better to hold off on publishing until things are more stable. Work and testing can be done on a separate branch for now.