Implement mvt databases

[shivagnihotri]

Good morning, lovely MaintainTeam! 🌻

I very much enjoy that the important mvt project exists and am not sure if Hypatia already uses the signatures provided there. If not, possibly add them so that Hypatia becomes an "Android mvt frontend"?

[Inhishonor]

The hashes are present here: https://github.com/mvt-project/mvt-indicators and seem to be updated, will definitely look into this.