Expose services to custom executor
With #2885 (closed) we added the MVC for the generic executor, which allows the user to setup their own environment.
We have the services keyword which can be useful when you have some kind of dependency on your job such as the database. If we expose this in the generic executor the users can set up their own services.
Since we already expose all the information as env variables we should stick to this convention, but since there can be multiple services we should suffix them with an index for exaple:
CUSTOM_ENV_SERVICE_0_NAME CUSTOM_ENV_SERVICE_0_ALIAS CUSTOM_ENV_SERVICE_1_NAME CUSTOM_ENV_SERVICE_1_ALIAS ...