Tracking package dependencies/environments

[dberenbaum]

Report

Background:
iterative/dvc#7378
iterative/dvc#6115
iterative/dvc#5758

We hear this come up regularly and it's probably time we add something to the docs about it. I think we could start with something like what's suggested in iterative/dvc#7378. Or we could show a couple different methods, like suggesting docker as a "best practice" but also showing iterative/dvc#7378 as an alternative if docker is too heavy.

A further request that has come up is to track the dependencies granularly per stage since a single package update should not necessarily trigger running the entire pipeline. Is there a way we could track the output of pip freeze like parameters?