Add button to open an item in an app

[pipe01]

Is your proposal related to a problem?

There's currently no good way to let Android know what URLs a Lemmy app can open since they all have different domains.

Describe the solution you'd like.

If we add a button/link on all posts (and possibly other items too) that opens a URL with a custom protocol (e.g. lemmy://lemmy.ml/p/1234), an Android app will then be able to register an intent filter for that URL protocol and open it in itself.

Describe alternatives you've considered.

The way that Jerboa does it is by hardcoding certain dominas, but that's untenable.

Additional context

I could work on this if you think it's a good idea.