chore: adds JavaScript quality checks workflow

Implements a GitHub Actions workflow to automatically lint JavaScript code in the `src` directory on pull requests and pushes to the main branch.

This ensures code quality and consistency by running `wp-script lint:js` on the specified files.

The workflow also configures concurrency to cancel in-progress runs for pull requests, preventing redundant checks.

Author: firestar300

.github/workflows/quality-js.yml

@@ -0,0 +1,38 @@
+name: Javascript Quality Checks
+
+on:
+  pull_request:
+      paths:
+          - 'src/**'
+  push:
+      paths:
+          - 'src/**'
+      branches:
+      - main
+
+# Cancels all previous workflow runs for pull requests that have not completed.
+concurrency:
+  # The concurrency group contains the workflow name and the branch name for pull requests
+  # or the commit hash for any other events.
+  group: ${{ github.workflow }}-${{ github.event_name == 'pull_request' && github.head_ref || github.sha }}
+  cancel-in-progress: true
+
+jobs:
+  checks:
+    name: Lint JS
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout project
+        uses: actions/checkout@v3
+
+      - name: Setup NodeJS
+        uses: actions/setup-node@v4
+        with:
+            node-version-file: 'package.json'
+
+      - name: Install npm dependencies
+        run: npm ci
+
+      - name: Run wp-script lint:js on src folder
+        run: npm run lint:js src