Manage permissions for persons (users) and groups (Django groups) in frontend

There are views needed for

• assigning global permissions to persons (users)
• assigning global permissions to groups (django groups)
• assigning permissions for persons according to objects
• assigning permissions for groups according to objects
• showing permissions
• deleting permissions

1/2 must interact with built-in permission system, 3/4 with django-guardian.

added part::frontend prio::3 type::feature workflow::discussing labels

changed title from Manage permissions for persons (users) and groups (django groups) in frontend to Manage permissions for persons (users) and groups (Django groups) in frontend

assigned to @hansegucker

created merge request !533 (merged) to address this issue

mentioned in merge request !533 (merged)

changed the description

marked the checklist item assigning global permissions to persons (users) as completed

marked the checklist item assigning global permissions to groups (django groups) as completed

marked the checklist item assigning permissions for persons according to objects as completed

marked the checklist item assigning permissions for groups according to objects as completed

marked the checklist item showing permissions as completed

marked the checklist item deleting permissions as completed

assigned to @ZugBahnHof and unassigned @hansegucker

mentioned in issue #219

assigned to @hansegucker and unassigned @ZugBahnHof

mentioned in commit 02f69313

closed with merge request !533 (merged)