* state: add simple reentrance
* state: pass Repo instead of LocalCache
* state: use granularly
Users could still load state preemptively if they want to bulk up
the operations, but other than that tree/cache will just load it
when they need it.
We used to use that logic in DvcTree back before we had proper trees.
Now we have a RepoTree, that combines git/workspace tree with the
DvcTree and dirty state clearly belongs to the git/workspace and not
the dvc itself, as dvc state only depends on dvc-files and lock-files.
Prerequisite for #4523
* dvc: use cache state when saving downloaded cache
Related to #4485
* tree: dont compute hash from scratch for output dirs
Fixes#4485
* tree: fix get_hash
Ruslan Kuprieiev
