Document upload

* adds document upload form
* refactors modal form templates into form classes
* adds document upload route to intervention routes of urls.py

compensation/forms.py

@@ -48,6 +48,7 @@ class NewPaymentForm(BaseModalForm):
     )
 
     def __init__(self, *args, **kwargs):
+        self.template = "modal/modal_form.html"
         super().__init__(*args, **kwargs)
         self.intervention = self.instance
         self.form_title = _("Payment")