[Fixes #14274] Enable importing a remote resource from a private WMS service

[sijandh35]

Fixes #14274

Checklist

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[gemini-code-assist]

Code Review

This pull request adds support for authentication configurations when importing remote WMS services, updating serializers, thumbnail generation, and resource payload generation to handle credentials, alongside adding corresponding unit tests. The review feedback highlights several critical issues, including a potential runtime TypeError when instantiating AuthConfig with a non-field property, a potential DoesNotExist exception when fetching an authentication configuration, and potential ValueError exceptions if queries are performed with an unauthenticated or null user.

[codecov]

Codecov Report

❌ Patch coverage is 86.18785% with 25 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.89%. Comparing base (91c4ec5) to head (d2c34bc).
⚠️ Report is 18 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #14285      +/-   ##
==========================================
- Coverage   74.92%   74.89%   -0.04%     
==========================================
  Files         975      977       +2     
  Lines       59902    60233     +331     
  Branches     8157     8213      +56     
==========================================
+ Hits        44884    45109     +225     
- Misses      13194    13299     +105     
- Partials     1824     1825       +1     

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