Sanitize metadata input

[etj]

Sanitizes metadata.
Also provides a label-i18n thesaurus for localization of the metadata editor messages.

Checklist

Reviewing is a process done by project maintainers, mostly on a volunteer basis. We try to keep the overhead as small as possible and appreciate if you help us to do so by completing the following items. Feel free to ask in a comment if you have troubles with any of them.

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• There is a ticket in https://github.com/GeoNode/geonode/issues describing the issue/improvement/feature (a notable exemption is, changes not visible to end-users)
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Submitting the PR does not require you to check all items, but by the time it gets merged, they should be either satisfied or inapplicable.

[codecov]

Codecov Report

❌ Patch coverage is 97.82609% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.94%. Comparing base (83c280b) to head (a05259c).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #14322      +/-   ##
==========================================
+ Coverage   74.91%   74.94%   +0.02%     
==========================================
  Files         982      983       +1     
  Lines       60496    60584      +88     
  Branches     8247     8261      +14     
==========================================
+ Hits        45322    45403      +81     
- Misses      13344    13351       +7     
  Partials     1830     1830              

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.