Permissions Registry and permissions handler

[mattiagiupponi]

Overview

The permissions in geonode are static, GeoNode itself is the only one who can decide the permissions to be assigned to a resource. This is not always true because my thrid party application may want to override a specific permissions and provide it by default.
Some workflow may not be required to be included by default in GeoNode (like advanced workflow) but just activated if needed

Proposed By

@mattiagiupponi

Assigned to Release

GeoNode 5.x

Proposal

We will create a PermissionsRegistry where GeoNode and other apps can register their own PermissionsHandler which will be responsible to add/change/modify the permissions payload before save it.
The read permissions part will not be changed since it will automatically get the changes applied on the permissiosn

Backwards Compatibility

None