repro: support running stage via it's output's name

[skshetry]

We should probably accept an output as a target.
It can solve some problems with autocomplete and improve experience. Related #3743 (especially last comments).

$ dvc repro model.pkl

Originally posted by @shcheklein in #3777

[efiop]

looks like moving to collect_granular in

dvc/dvc/repo/reproduce.py

Line 117 in f09c27e

targets = self.stage.collect(

, should do the trick.

[skshetry]

@efiop, globbing is not possible with collect_granular(). So, either we should use different function based on glob or if we want to make globbing default, we do not support this at all.

[efiop]

@skshetry I didn't mean globbing, just output -> dvcfile mapping.

[Vonski]

I can do this one. Could I take it?

[Vonski]

For now collect_granular, if provided with glob that matches any out files, returns the same PathInfo for all found stages. This PathInfo is created directly from provided glob. Sometimes filter_info from collect_granular is used further and can end up being passed to methods like path_info.isin_or_eq which do not handle globs. If someone in the future try to add glob=True argument to call of collect_granular in places like for example Repo.used_cache or commit method from dvc/repo/commit.py then it may not work as expected, because returned filter_info is used after that and is built from glob.

[jorgeorpinel]

Hi. Should this also apply to status and maybe run?