Thesauri: editing GUI

[etj]

Modify the editing GUI so that thesauri selection is rendered in the first tab.

We want to display all of the thesauri set as required in the GUI.
The requirement is set in the DB (card_min, card_max), but we also have a legacy setting (https://docs.geonode.org/en/2.10/admin/thesaurus/index.html#configure-a-thesaurus-in-geonode)

In the GUI,

• card_max=0 --> Disabled, won't be shown in the GUI (card_min is not even checked in this case)
• card_max=1 --> Single choice
  • card_min = 0 --> Single choice, optional --> rendered as a dropdown, with an empty/unselected element
  • card_min = 1 --> Single choice, required --> rendered as a dropdown
• card_max=-1 --> Multiple choice
  • card_min = 0 --> [0..N] Multiple choices, optional --> rendered as a typeahead badges(?)
  • card_min = 1 --> [1..N] Multiple choices, required --> rendered as a typeahead badges(?) + apply check for the mandatory warning

If the legacy required boolean setting is in the configuration, we'll use it as if we'd found:

• required = true
  • card_min = 1
  • card_max = -1
• required = false
  • card_min = 0
  • card_max = -1

As stated in #11, when a legacy settings is found, we'll use it and notify a warning about the deprecated setting.

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GUI should be restructed as follows:

• free keywords moved to the bottom
• list of Thesauri keywords selectors

Also, the validation checks should act according to the mandatory requirements of the displayed thesauri.