GDrive improvements and code cleanup

[shcheklein]

It's a major rewrite now. It was needed since it was very hard an unproductive fixing certain issues w/o addressing some underlying problems with code.

• Performance of remote id resolving improved. It does not hit API now for "remote path". Affects pull - one API call per file less!
• Performance of the first run should be improved. We now cache path->id as we create them (case when we push a lot first time we create a remote).
• Number of retries increased. The previous was not enough with default GDrive limits.
• Does not create remote path anymore (see the Stop creating a path to the DVC remote root if it does not exist checkbox) in Google Drive support further enhancements #2865
• Code cleanup.

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• ❗ Have you followed the guidelines in the Contributing to DVC list?

• 📖 Check this box if this PR does not require documentation updates, or if it does and you have created a separate PR in dvc.org with such updates (or at least opened an issue about it in that repo). Please link below to your PR (or issue) in the dvc.org repo.

• ❌ Have you checked DeepSource, CodeClimate, and other sanity checks below? We consider their findings recommendatory and don't expect everything to be addressed. Please review them carefully and fix those that actually improve code or fix bugs.

Thank you for the contribution - we'll try to review it as soon as possible. 🙏

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@2aff0a0). Click here to learn what that means.
The diff coverage is 96.42%.

@@            Coverage Diff            @@
##             master    #3294   +/-   ##
=========================================
  Coverage          ?   92.83%           
=========================================
  Files             ?      139           
  Lines             ?     8541           
  Branches          ?        0           
=========================================
  Hits              ?     7929           
  Misses            ?      612           
  Partials          ?        0

Impacted Files	Coverage Δ
dvc/command/imp.py	86.36% <ø> (ø)
dvc/exceptions.py	97.27% <ø> (ø)
dvc/command/metrics.py	96.82% <ø> (ø)
dvc/command/get.py	91.89% <100%> (ø)
dvc/output/local.py	98.27% <100%> (ø)
dvc/repo/metrics/diff.py	95.38% <100%> (ø)
dvc/repo/diff.py	100% <100%> (ø)
dvc/repo/reproduce.py	98.66% <100%> (ø)
dvc/command/diff.py	92.85% <100%> (ø)
dvc/repo/__init__.py	96.76% <88.88%> (ø)

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[shcheklein]

@efiop I suggest we review codeclimate and deepsource settings a bit and make the more useful/less noisy for us. E.g. number of arguments per function - if we think that 4 is to aggressive let's increase it a bit?

[maxhora]

looks great to me! 👍