Stabilize playwright tests by making the left panel constant width (#33451)

* Move css injection to panel.ts

- Inject css on event

* Upgrade package

* Fix playwright tests

* Remove RR instead of masking it

* Fix wrong import

* Fix playwright tests

* Fix more playwright tests

* Catch error and add comment

apps/web/playwright/e2e/composer/CIDER.spec.ts

@@ -20,6 +20,7 @@ test.describe("Composer", () => {
         botCreateOpts: {
             displayName: "Bob",
         },
+        lockLeftPanelWidth: false,
     });
 
     test.use({
@@ -185,6 +186,7 @@ test.describe("Composer", () => {
             await app.viewRoomByName("Bob");
 
             const composer = page.getByRole("textbox", { name: "Send an unencrypted message…" });
+            await composer.click();
             await composer.pressSequentially("@bob");
 
             // Note that we include the user ID here as the room tile is also an 'option' role