[#3950] Make service catalogue more consistent with Signicat template

[SilviaAmAm]

Fixes open-formulieren/open-forms#3950 (first checkbox)

Context
Signicat, one of the Identity Providers for eHerkenning, said that the service catalogue that we generated was 'invalid'. The Signicat template can be found here: https://developer.signicat.com/broker/eherkenning-broker/eherkenning-service-catalogue.html#introduction

The noticed differences are mentioned in the ticket.

The service catalogue gets validated against this XSD: https://afsprakenstelsel.etoegang.nl/display/as/Service+catalog (under XML schema Service Catalog)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.10%. Comparing base (970d3ed) to head (38ef6ed).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #63      +/-   ##
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+ Coverage   96.01%   96.10%   +0.08%     
==========================================
  Files          72       73       +1     
  Lines        3216     3260      +44     
==========================================
+ Hits         3088     3133      +45     
+ Misses        128      127       -1     

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[vaszig]

Don't have a lot of experience in xml-xsd so I don't find something weird.

I am not sure about the last bullet in the task "They don't have the signature node => The XSD has no value for the minOccurs and the default is 1 (https://www.w3.org/TR/xmlschema-0/#OccurrenceConstraints). So I think we need to leave this field in?"

I guess you are right.

[SilviaAmAm]

Discussion with Joeri:

• Re-add the sets for entity concernde types allowed
• Update tests with requested attributes. These should have been for eIDAS, not eH. Also, add them to the defaults. And add documentation.
• Make a new ticket in OF about using every requestedAttribute in the auth variable => Include all RequestedAttribute in the auth variable open-formulieren/open-forms#3985
• Update the esc:Version at the top of the catalogue (check also metadata)