FCL-1843 | add VCR with fixtures for isolated E2E test running

[jlhdxw]

Changes in this PR:

This adds VCR to allow us to record and playback responses from external services. This means when we run E2E tests, we can test them against consistent responses in dev and CI.

Jira card / Rollbar error (etc)

https://national-archives.atlassian.net/browse/FCL-1843

[dragon-dxw]

I'm dubious about the maturity of the VCR framework given the amount of extra effort you had to put into it to make it do its job.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.65%. Comparing base (74565c9) to head (0823643).
⚠️ Report is 26 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2892   +/-   ##
=======================================
  Coverage   95.65%   95.65%           
=======================================
  Files          97       97           
  Lines        3568     3568           
  Branches      145      145           
=======================================
  Hits         3413     3413           
  Misses        115      115           
  Partials       40       40           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.