tests/playwright: Add Hostname customization test

Adds a Hostname customization test that creates a BP, edits BP, exports and imports it back and verifies the BP content.
This test also servers as a template for other customization tests. Includes a refactor of existing helper functions.

playwright/fixtures/cleanup.ts

@@ -0,0 +1,45 @@
+import { test as oldTest } from '@playwright/test';
+
+type WithCleanup = {
+  cleanup: Cleanup;
+};
+
+export interface Cleanup {
+  add: (cleanupFn: () => Promise<unknown>) => symbol;
+  runAndAdd: (cleanupFn: () => Promise<unknown>) => Promise<symbol>;
+  remove: (key: symbol) => void;
+}
+
+export const test = oldTest.extend<WithCleanup>({
+  // eslint-disable-next-line no-empty-pattern
+  cleanup: async ({}, use) => {
+    const cleanupFns: Map<symbol, () => Promise<unknown>> = new Map();
+
+    // eslint-disable-next-line react-hooks/rules-of-hooks
+    await use({
+      add: (cleanupFn) => {
+        const key = Symbol();
+        cleanupFns.set(key, cleanupFn);
+        return key;
+      },
+      runAndAdd: async (cleanupFn) => {
+        await cleanupFn();
+
+        const key = Symbol();
+        cleanupFns.set(key, cleanupFn);
+        return key;
+      },
+      remove: (key) => {
+        cleanupFns.delete(key);
+      },
+    });
+
+    await test.step(
+      'Post-test cleanup',
+      async () => {
+        await Promise.all(Array.from(cleanupFns).map(([, fn]) => fn()));
+      },
+      { box: true }
+    );
+  },
+});