Adding code quality check for a PR.

Author: colinmurphy

.github/workflows/code-quality.yml

@@ -0,0 +1,46 @@
+name: Code Quality
+
+on:
+  pull_request:
+    paths:
+      - 'plugins/**'
+
+jobs:
+  run:
+    runs-on: ubuntu-latest
+    name: Check code quality
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Get changed plugin directory
+        id: plugin
+        run: |
+          git fetch --prune --unshallow
+          plugin=$(git diff --name-only ${{ github.event.pull_request.base.sha }} ${{ github.sha }} | grep '^plugins/' | head -1 | cut -d/ -f2)
+          echo "slug=$plugin" >> $GITHUB_OUTPUT
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '7.4'
+          tools: composer:v2
+          coverage: none
+
+      - name: Install dependencies
+        uses: ramsey/composer-install@v2
+        with:
+          composer-options: "--no-progress"
+
+      - name: Run PHP CodeSniffer
+        working-directory: plugins/${{ steps.plugin.outputs.slug }}
+        run: composer run-script phpcs
+
+      - name: Run PHPStan
+        working-directory: plugins/${{ steps.plugin.outputs.slug }}
+        run: composer run-script phpstan
+
+      - name: Run Psalm
+        working-directory: plugins/${{ steps.plugin.outputs.slug }}
+        run: composer run-script psalm