Fix closing all modals (#12728)

* Fix closing all modals

We used `Modal.closeCurrentModal()` in a bunch of places, in all cases
(as far as I can see: it wasn't commented) we meant to close all open
modals. This swaps that function for one that closes all open modals.

Also types the close reason which claimed to be something in a comment,
of course, was wrong because a load of places passed their own random
string which was never used.

* Force close modals

* Try with minimal changes

* Already had a method for this

* Add test

* More tests

* Unused importsd

test/Modal-test.ts

@@ -0,0 +1,32 @@
+/*
+Copyright 2024 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import Modal from "../src/Modal";
+import QuestionDialog from "../src/components/views/dialogs/QuestionDialog";
+
+describe("Modal", () => {
+    test("forceCloseAllModals should close all open modals", () => {
+        Modal.createDialog(QuestionDialog, {
+            title: "Test dialog",
+            description: "This is a test dialog",
+            button: "Word",
+        });
+
+        expect(Modal.hasDialogs()).toBe(true);
+        Modal.forceCloseAllModals();
+        expect(Modal.hasDialogs()).toBe(false);
+    });
+});