[Fixes: #7033] Mandatory fields in editor

[mattiagiupponi]

In order to fix issue #7033 regarding the mandatory fields in the editor, I want to introduce new settings named `` which will set on UI the fields mandatory based on the settings list.
By default, all fields will stay optional.

NOTE: as most of the geonode fields, the mandatory is just from UI perspective

PR for documentation is available here => GeoNode/documentation#84

Checklist

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