Run the CLI tests in CI

Right now, the inspector has a CLI feature as well as a series of tests.
However, they're not currently run in CI. For the moment, they are only
triggered on file changes in the CLI folder, as AFAICT it is currently a
separate code base.

.github/workflows/cli_tests.yml

@@ -0,0 +1,26 @@
+name: CLI Tests
+
+on:
+  push:
+    paths:
+      - 'cli/**'
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: ./cli
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v2
+        with:
+          node-version: '14'
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run tests
+        run: npm test