🐛 [#4713] Fix token exchange for BRP client

[stevenbal]

Closes #4713

Changes

• Set up Docker mock service for HaalCentraal BRP
• Fix token exchange for BRP client

Checklist

Check off the items that are completed or not relevant.

• Impact on features

  • Checked copying a form
  • Checked import/export of a form
  • Config checks in the configuration overview admin page
  • Problem detection in the admin email digest is handled

• Release management

  • I have labelled the PR as "needs-backport" accordingly

• I have updated the translations assets (you do NOT need to provide translations)

  • Ran ./bin/makemessages_js.sh
  • Ran ./bin/compilemessages_js.sh

• Commit hygiene

  • Commit messages refer to the relevant Github issue
  • Commit messages explain the "why" of change, not the how

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.56%. Comparing base (961e607) to head (7393002).
Report is 683 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4740   +/-   ##
=======================================
  Coverage   96.56%   96.56%           
=======================================
  Files         746      746           
  Lines       25185    25187    +2     
  Branches     3312     3313    +1     
=======================================
+ Hits        24320    24322    +2     
  Misses        601      601           
  Partials      264      264           

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

[sergei-maertens]

I don't understand why chromatic is failing 🤔

[sergei-maertens]

I don't understand why chromatic is failing 🤔

okay looks like I broke it with the refactor, https://open-formulieren.github.io/open-forms/?path=/story/form-design-variablemapping--select-options is also failing. I'll look into it!

[sergei-maertens]

Backports:

• 2.8.x: 83cd868
• 2.7.x: b624ac1