Add M3 theme and apply to AboutActivity

[rfc2822]

See #691

• rename M2 AppTheme to M2Theme
• create new M3 theme (still subject to adaptions of colors etc.) as AppTheme
• apply M3 theme to AboutActivity
• replace LiveData by Compose state in OpenSourceLicenseInfoProvider.Model
• make links in GPL text clickable

@ArnyminerZ @devvv4ever @sunkup What do you think? We could gradually rewrite the activities to M3 (again one after each other with an issue/PR per activity, I'll create the issues).

[ArnyminerZ]

Everything else looks good 😉

[devvv4ever]

Could you make a build/screenshots with the "inverse" colors I provided?

Basically the above looks correct, however not totally appealing, since I always miss the ability to use our very own colors. The colors are always adapted for contrast and readability, which is useful of course but it just not pleases me :P

[sunkup]

Basically the above looks correct, however not totally appealing, since I always miss the ability to use our very own colors. The colors are always adapted for contrast and readability, which is useful of course but it just not pleases me :P

Agree with you on this one. I really don't like the purple/brown-ish hue of the background ...

It was similar with ICSx5 where I ended up declaring the background to be pure white - which still goes well with the other generated color nuances.