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

[SilviaAmAm]

Fixes https://github.com/open-formulieren/open-forms/issues/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[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

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

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #63 +/- ## ========================================== + 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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[SilviaAmAm]

Discussion with Joeri:

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