Add a layout reset function

For https://github.com/vector-im/riot-web/issues/14265

Intended to be accessed via `mx_RoomListStore2.resetLayout()`

src/stores/room-list/ListLayout.ts

@@ -120,6 +120,10 @@ export class ListLayout {
         return px / this.tileHeight;
     }
 
+    public reset() {
+        localStorage.removeItem(this.key);
+    }
+
     private save() {
         localStorage.setItem(this.key, JSON.stringify(this.serialize()));
     }

src/stores/room-list/RoomListStore2.ts

@@ -30,6 +30,7 @@ import { TagWatcher } from "./TagWatcher";
 import RoomViewStore from "../RoomViewStore";
 import { Algorithm, LIST_UPDATED_EVENT } from "./algorithms/Algorithm";
 import { EffectiveMembership, getEffectiveMembership } from "./membership";
+import { ListLayout } from "./ListLayout";
 
 interface IState {
     tagsEnabled?: boolean;
@@ -401,6 +402,15 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
         this.emit(LISTS_UPDATE_EVENT, this);
     }
 
+    // Note: this primarily exists for debugging, and isn't really intended to be used by anything.
+    public async resetLayouts() {
+        console.warn("Resetting layouts for room list");
+        for (const tagId of Object.keys(this.orderedLists)) {
+            new ListLayout(tagId).reset();
+        }
+        await this.regenerateAllLists();
+    }
+
     public addFilter(filter: IFilterCondition): void {
         // TODO: Remove debug: https://github.com/vector-im/riot-web/issues/14035
         console.log("Adding filter condition:", filter);