Add encrypt/decrypt vehicle

[Jako]

It allows to encrypt the package with the build option encrypt. The package will be encrypted with the key in gitpackagemanagement.encrypt_key or with the CLI encryptKey property. During the installation the package provider has to send the key with the endpoint package/decode/install or package/decode/uninstall

The vehicle adds the gitpackagemanagement.support_mail, gitpackagemanagement.support_name and the gitpackagemanagement.support_url system setting values into the payload to provide some better error messages to the customer, when the package can't be decrypted.

To use the encrypt option, you have to add a resolve.encrypted.php resolver on base of the encrypt_resolver.tpl template. Maybe this can be automated somehow.