Do testing and bugfixing of /admin/receiver /admin/node and /admin/context

PT: #44142735, #43212607, #43212553, #43212587
Merge remote-tracking branch 'origin/refactor-db' into refactor-db

* origin/refactor-db:
  implemented Receiver/WB tip+folders access
  mergin

Conflicts:
	globaleaks/handlers/admin.py