feat: new command menu pt 1 (#23699)

Introduces the first (very small) slice of the new command menu as a `ui-pattern`.

This slice just handles state for available commands. It isn't hooked up to anything yet.

.github/workflows/ui-patterns-tests.yml

@@ -0,0 +1,34 @@
+name: UI Patterns Tests
+
+on:
+  pull_request:
+    branches: [master]
+    paths:
+      - 'packages/ui-patterns/**'
+
+# Cancel old builds on new commit for same workflow + branch/PR
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          sparse-checkout: |
+            packages
+
+      - name: Use Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version-file: '.nvmrc'
+          cache: 'npm'
+
+      - name: Install deps
+        run: npm ci
+
+      - name: Run tests
+        run: npm run test:ui-patterns