Add test coverage and remove MacOS integration tests

[woop]

Signed-off-by: Willem Pienaar git@willem.co

What this PR does / why we need it:

• Adds code coverage reporting using https://codecov.io/
• Removes integration tests for MacOs (unable to use Docker)

Does this PR introduce a user-facing change?:

NONE

[feast-ci-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: woop

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• OWNERS [woop]

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[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (master@77a7975). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #1562   +/-   ##
=========================================
  Coverage          ?   77.47%           
=========================================
  Files             ?       64           
  Lines             ?     5496           
  Branches          ?        0           
=========================================
  Hits              ?     4258           
  Misses            ?     1238           
  Partials          ?        0           

Flag	Coverage Δ
unittests	77.47% <0.00%> (?)

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