feat: add phpstan and phpcs to CI checks

Signed-off-by: Bart Jaskulski <bjaskulski@protonmail.com>

gitlab-ci-1.2.yml

 variables:
-  WPDESK_CI_VERSION: "2023.11.10"
+  WPDESK_CI_VERSION: "2023.11.17"
   MYSQL_ROOT_PASSWORD: "mysql"
   MYSQL_DATABASE: "wptest"
   MYSQL_USER: "mysql"
@@ -30,6 +30,7 @@ include:
     file:
       - '/includes/prepare.yml'
       - '/includes/translations.yml'
+      - '/includes/tests/static-analysis.yml'
       - '/includes/tests/lint.yml'
       - '/includes/tests/unit.yml'
       - '/includes/metrics.yml'

includes/tests/static-analysis.yml

+.static-analysis:
+  image: gitlab.wpdesk.dev:5050/wpdesk/docker-tests/php-box:8.2
+  needs:
+    - prepare prefixed vendor
+  stage: tests
+
+# Run phpstan in strict mode (failing pipeline) only if we have baseline, otherwise allow to fail with a warning, suggesting to create one. This behavior will change at the end of the year, when any PHPStan failure will be considered fatal
+phpstan:
+  extends: .static-analysis
+  script:
+    - |
+      if [ -f "vendor/bin/phpstan" ]; then
+        vendor/bin/phpstan analyse --memory-limit=2G
+      elif [ -f "vendor/wpdesk/wp-wpdesk-composer/director/vendor/bin/phpstan" ]; then
+        # PHPStan installed by director
+        vendor/wpdesk/wp-wpdesk-composer/director/vendor/bin/phpstan analyse --memory-limit=2G
+      else
+        echo "PHPStan not found! Install it with 'composer require --dev wpdesk/phpstan-rules'."
+        # We will be able to use custom exit after removing rules.allow_failure part
+        # exit 125
+      fi
+  allow_failure: true
+  rules:
+    - exists:
+      - .phpstan-baseline.php
+      - .phpstan-baseline.neon
+      allow_failure: false
+
+phpcs:
+  extends: .static-analysis
+  script:
+    - vendor/bin/phpcs
+  allow_failure: true
+  rules:
+    - exists:
+      - phpcs.xml.dist