Add scripts for drupal operations

Added scripts for:

• Clear cache
• DB backup
• DB restore
• Enabling maintenance mode
• Disabling maintenance mode
• Site install
• Check if site install was successful

Refers to https://gitlab.cern.ch/webservices/webframeworks-planning/-/issues/324

scripts/clear-cache.sh

+#!/bin/bash
+set -exu
+
+# Change working directory to the drupal code
+cd /app
+
+# Clean cache
+echo "Cleaning cache"
+drush cr