Check each new service key for duplicates

[KZzizzle]

There is currently no check that service keys for different services are unique. If a new service is created with the same key as an existing one, that new service will overwrite the previous one in the service catalog. This should probably be checked in:

https://git.speag.com/oSparc/sparc-external
https://git.speag.com/oSparc/sparc-internal
https://github.com/ITISFoundation/osparc-services

key=name of the service.
One solution : check in the CI if a service already exists before adding a new one ?