Migrations + Cleanup

* adds needed migrations
* refactors forms.py (700+ lines) in main konova app
    * splits into forms/ and forms/modals and single class/topic-files for better maintainability and overview
* fixes bug in main konova app migration which could occur if a certain compensation migration did not run before

konova/utils/documents.py

@@ -5,10 +5,9 @@ Contact: michel.peltriaux@sgdnord.rlp.de
 Created on: 01.09.21
 
 """
-from django.http import FileResponse, HttpRequest, HttpResponse, Http404
-from django.utils.translation import gettext_lazy as _
+from django.http import FileResponse, HttpRequest, Http404
 
-from konova.forms import RemoveModalForm
+from konova.forms.modals import RemoveModalForm
 from konova.models import AbstractDocument
 from konova.utils.message_templates import DOCUMENT_REMOVED_TEMPLATE