Dvc

* pull/checkout: fix empty log output if no state gets changed (3520) skshetry
* pull: support pulling git-only imports (3503) skshetry
* dvc: add Repo(skip_checks) flag (3490) Suor
* git: quote filenames at remind_to_track (3315) mroutis
* dvc: update cmd output strings to match docs (3471) jorgeorpinel
* external_repo: do not try too hard to fix upstream (3512) skshetry
* Revert "Restyle 3393 introduce hyper parameters and config" (3517) efiop
* Restyle 3393 introduce hyper parameters and config (3516) restyled-io
* import: fix output message on not-existing output directory (3509) skshetry
* version: fix bug when .git dir is removed, show more info regarding repo (3508) skshetry

* pipeline: fix `--outs` output (3507) efiop
* dvc: use consistent messages for InvalidArgumentError (3506) efiop

* git: tree: use item.path instead of item.name (3505) efiop

* version: add supported remotes (3498) efiop
* import-url: allow queries in URL (3432) casperdcl
* template: pr update (3495) casperdcl
* dvc: use protected mode by default (3472) efiop
* gc: do not work without specifier when using -c flag (3493) skshetry
* completion: add --summary flag on checkout (3491) skshetry

* logger: use standard lazy formatting (3487) efiop
* cmd: diff: don't load dir cache for diff (3468) pared
* dvc: support Python3.8 (3463) skshetry
* Use pre-commit for Git hooks (3406) andrewhare
* list: rename target param to path, update docs (3462) JIoJIaJIu
* exceptions: use semantic exceptions (3430) skshetry
* checkout: show summary by default and introduce --show-changes flag (3401) skshetry
* tests: remove use of mocker as context-manager (3480) skshetry
* dvc: optimize all target specific commands to not build graph (3459) Suor
* tests: add .gitignore files when upon dvc_add (3455) pared
* add: do not verify hardlink if file is empty (3428) skshetry
* api: docstring updates (2) (3426) jorgeorpinel
* completion: bash: misc fixes and updates (3467) casperdcl
* gdrive: support Google Service accounts (3269) MaxRis

* deps: upgrade jsonpath_ng to latest version (3464) skshetry
* gc: make --all-commits flag visible (3429) skshetry
* gdrive: share drive vs just folder id when we set corpora param (3458) shcheklein
* list: colorize output (3351) JIoJIaJIu
* dvc: optimize building graph (3443) Suor
* metrics show: update -h output to match docs (3420) jorgeorpinel
* pipelines: fix edges gathering (3421) pared
* test: check that no remote backend modules are loaded by default (3400) Suor