[#6217] allow choosing document summaries for ZGW registrations

[SonnyBA]

Closes #6217

Changes

Allows form builders to specify which registration summary documents they want to include for requests to the configured ZGW API:

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
  • Checked new model fields are usable in the admin
  • Problem detection in the admin email digest is handled

• Dockerfile/scripts

  • Updated the Dockerfile with the necessary scripts from the ./bin folder

• Commit hygiene

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

• Documentation

  • Added documentation which describes the changes

[skip: e2e]

[codecov]

Codecov Report

❌ Patch coverage is 98.21429% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 97.07%. Comparing base (f9695ad) to head (6204449).

Files with missing lines	Patch %	Lines
...penforms/registrations/contrib/zgw_apis/options.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6299   +/-   ##
=======================================
  Coverage   97.07%   97.07%           
=======================================
  Files         866      868    +2     
  Lines       32755    32798   +43     
  Branches     2981     2983    +2     
=======================================
+ Hits        31797    31839   +42     
- Misses        646      647    +1     
  Partials      312      312           

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[viktorvanwijk]

A few questions/remarks about this:

1. What exactly are you trying to achieve here? Won't all_values just equal values at the end?
2. Iterating over a FormioData instance is not allowed, because you will not get the full variable keys if there is nested data. For example, component with key "foo.bar" will be present in the data as {"foo": {"bar": "baz"}}, so iterating over it will just give you "foo".
3. Does it make sense to include static variables here? I don't think they are in the PDF summary right?

Also, I think we need some processing of the values and schema here. Looking at the generic json plugin, partners and children data need to be cleaned up. Also, I'm not sure if it makes sense to include the submission data from file components as is, because it just contains metadata about the upload to the server. Would it be possible to relate it to the created attachment documents, like in the Objects API?

Given that it's the third plugin that requires this data cleanup, perhaps this is the part that can be refactored/generalized? Specifically processing partners and children will be the same for all plugins I think. (still a bit unclear to me whether this is worth it tbh, because there is also plugin-specific things happening)