feat(quick-start): Add analytics code to the backend to track quick start completion

[priscilawebdev]

Contributes to https://github.com/getsentry/projects/issues/251

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #79089      +/-   ##
==========================================
- Coverage   78.29%   78.29%   -0.01%     
==========================================
  Files        7132     7132              
  Lines      313945   313949       +4     
  Branches    51259    51259              
==========================================
- Hits       245814   245801      -13     
- Misses      61707    61719      +12     
- Partials     6424     6429       +5     

[sentry-io]

Suspect Issues

This pull request was deployed and Sentry observed the following issues:

• ‼️ KeyError: 'onboarding.complete' /api/0/issues|groups/{issue_id}/plugins/asana/c... View Issue
• ‼️ KeyError: 'onboarding.complete' /api/0/organizations/{organization_id_or_slug}/... View Issue

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