metrics/plots: initial support non-dvc repos

[efiop]

Initial hacky support, that still tries to create .dvc directory as a side-effect. That side effect will be addressed in the upcoming
PR. This feature in general makes us really rethink what a dvc repo is and whether having .dvc is really required.

• ❗ I have followed the Contributing to DVC checklist.

• 📖 If this PR requires documentation updates, I have created a separate PR (or issue, at least) in dvc.org and linked it here.

Thank you for the contribution - we'll try to review it as soon as possible. 🙏

[efiop]

We might consider getting rid of this in the future (for now needed for backward compatibility). Currently dvc init doesn't do much useful things and all .dvc contents could be (and should probably) be created dynamically.

Even things like dvc add could potentially just work in a pure git repo. Just something to think about...

[jorgeorpinel]

This feature in general makes us really rethink what a dvc repo is and whether having .dvc is really required.

Interesting (and I've noticed this mentioned elsewhere) can you elaborate a little? Or is there a discussion somewhere I can keep an eye and participate on this idea? Thanks

[efiop]

@jorgeorpinel Not yet, only verbal discussions at this point. We'll probably create something in the future.