Feature: implement use_constraints with restrictioncodes

[mwallschlaeger]

Feature Description

COMPLICATED TO DESCRIBE, ASK @mwallschlaeger for details

We're decided to have a two part approach for constraints:

1. use constraints for defined constraints by us (zalf) with 3 default restrictionscodes (copyright, ...)
2. other constraints for user defined constraints with default restrictionscode (other restrichtions)
   .

Upstream geonode implements this with Restrictions and Other constraints like:

This we can use to impl. 2. as it is exactly what we need.

for 1. we need to reimplement the field use_constraints (which is in zalf/geonode, but not in the way we need it) to be a free text field, and another field use_constraints_restrictions which holds the restriction codes applied to use_constraints so they can also be written to the xml like:

   <gmd:resourceConstraints>
         <gmd:MD_LegalConstraints>
           <gmd:useConstraints>
              <gmd:MD_RestrictionCode codeSpace="ISOTC211/19115" codeList="http://www.isotc211.org/2005/resources/Codelist/gmxCodelists.xml#MD_RestrictionCode" codeListValue="limitation not listed">limitation not listed</gmd:MD_RestrictionCode>
           </gmd:useConstraints>
           <gmd:otherConstraints>
             <gco:CharacterString>CC BYgfdhfg</gco:CharacterString>
           </gmd:otherConstraints>
         </gmd:MD_LegalConstraints>
       </gmd:resourceConstraints>

tasks todo:

• make sure use_constraints and other_constraints are in geonode.base.models.ResourceBase and described well
• check that there are two fields that are referencing to restrction_codes, use_constraints_restrictions and other_constraints_restrictions, best impliment both as onetomany, they can share the same database table in the backend
• make sure the fields are available as forms in the metadata editor
• make sure the fields are available in the resourcebase API and editable via API
• make sure both combinations are part of the geonode.catalogue.templates.full_metadata.xml
• check if also changes to pycsw local_mapping need to take place

PART OF #9