chore: use CircleCI workflows

[layershifter]

This PR updates existing CircleCI config to run test and lint jobs in parallel. Also provides some minor updates to config:

• use Node 12
• remove yarn install as it is included to Docker image
• code coverage is reported earlier to get reports faster

Inspired by yarnpkg/yarn#4271.

[codecov-commenter]

Codecov Report

Merging #3993 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3993   +/-   ##
=======================================
  Coverage   99.84%   99.84%           
=======================================
  Files         183      183           
  Lines        3157     3157           
=======================================
  Hits         3152     3152           
  Misses          5        5           

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