Improve modal accessibility

Implement initial focus for modals. Change all modals including forms to put initial focus on the first input. When Enter is pressed on any input (CTRL + Enter for Textareas), the form is submitted if it is valid.

Co-authored-by: Sebastian Sdorra <sebastian.sdorra@cloudogu.com>
Co-authored-by: Eduard Heimbuch <eduard.heimbuch@cloudogu.com>

scm-ui/ui-webapp/src/repos/containers/DeleteRepo.tsx

@@ -71,7 +71,8 @@ const DeleteRepo: FC<Props> = ({ repository, confirmDialog = true }) => {
           },
           {
             label: t("deleteRepo.confirmAlert.cancel"),
-            onClick: () => null
+            onClick: () => null,
+            autofocus: true
           }
         ]}
         close={() => setShowConfirmAlert(false)}