Add Product to the ZGW API registration

[robinmolen]

Closes #4796

Changes

Added product as a configuration option to the ZGW API registration. The product select gets populated from the selected case type. If there are multiple versions of the case type, then the case type version that is active at the moment of configuring is chosen.

Checklist

Check off the items that are completed or not relevant.

• Impact on features

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

• Release management

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

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

  • [x] Ran ./bin/makemessages_js.sh
  • [x] Ran ./bin/compilemessages_js.sh

• Commit hygiene

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

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 91.07143% with 5 lines in your changes missing coverage. Please review.

Project coverage is 96.57%. Comparing base (77e2cd6) to head (a50050b). Report is 15 commits behind head on master.

Files with missing lines	Patch %	Lines
src/openforms/contrib/zgw/products_and_services.py	75.00%	4 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #4803 +/- ## ========================================== - Coverage 96.58% 96.57% -0.01% ========================================== Files 748 749 +1 Lines 25477 25531 +54 Branches 3368 3376 +8 ========================================== + Hits 24606 24656 +50 - Misses 608 612 +4 Partials 263 263 ```

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