Add Copilot Usage Summary for Organization

[claystation]

Github has a Rest API to get the usage summary of Copilot within the organization. This PR implements the functionality to fetch that data.
API Docs: Here

Please let me know what you think!

[google-cla]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.06%. Comparing base (2b8c7fa) to head (d45f521).
Report is 144 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3318      +/-   ##
==========================================
- Coverage   97.72%   93.06%   -4.67%     
==========================================
  Files         153      172      +19     
  Lines       13390    11773    -1617     
==========================================
- Hits        13085    10956    -2129     
- Misses        215      723     +508     
- Partials       90       94       +4     

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[gmlewis]

Thank you, @claystation !
Just a few tweaks, please, then we should be ready for a second LGTM+Approval from any other contributor to this repo (and signed CLA) before merging.

[claystation]

@gmlewis i will close this PR due to CLA signing issues. I opened #3321 which also contains a commit with the requested changes. Please review that one, i hope it should be good!