Add individual purge buttons in Admin Trash page

[cgoldshtein]

Problem

The Admin Trash page (/ckan-admin/trash) only allows bulk purging of all deleted entities of a type. Clicking "Purge" for datasets/organizations/groups purges all entities of that type, with no way to selectively purge individual items.

Current code: TrashView.purge_entity() in ckan/ckan/views/admin.py iterates through all entities.

Proposed Solution

Add individual purge buttons for each entity in the trash list, allowing selective purging.

Backend - Modify TrashView.post():

def post(self) -> Response:
    entity_id = request.form.get(u'id', '')  # NEW
    
    if entity_id:  # NEW: Purge single entity
        logic.get_action(self._get_purge_action(req_action))(
            {u'user': current_user.name}, {u'id': entity_id}
        )
    elif req_action in (u'package', u'organization', u'group'):
        self.purge_entity(req_action)  # Existing bulk purge

Frontend - Add button per entity in template:

<form method="POST" action="{{ h.url_for('admin.trash') }}">
  {{ h.csrf_input() }}
  <input type="hidden" name="action" value="{{ ent_type }}">
  <input type="hidden" name="id" value="{{ entity.id }}">
  <button type="submit" class="btn btn-danger btn-sm">Purge</button>
</form>

Benefits

• Selective purging instead of all-or-nothing

• Reduces accidental data loss

• Maintains backward compatibility (bulk purge remains)

Files affected: ckan/ckan/views/admin.py, ckan/ckan/templates-bs3/admin/trash.html