Split out grumphp configuration into magento2 and pimcore options

[Anve94]

• Create new grumphp config for magento projects
• Create new grumphp config for pimcore projects
• Add reference to default in new grumphp config files
• Add support for pimcore projects in composer project type resolvement
• Automatically override local grumphp references to point to new configuration file after composer install or update
• Update changelog with latest changes