Use `dependencies` command from Metro

[grabbou]

Now, that our PR is merged, we could easily use dependencies command from Metro, instead of the code we have here.

[Esemesek]

Since we deprecated dependencies in the current release, we might even remove this command entirely. WDYT?

[grabbou]

That's what deprecation message says, yay!

[sidferreira]

Is this one done? Just need to add a deprecation message?

[thymikee]

This is technically a breaking change, but since RN 0.59 (which is our main consumer at the moment) is not out yet, I think we can squeeze this without semver major update. What do you think @grabbou?