[IDM.PCM.CLOUD] Develop plugin discovery backend

Create the service which:

• must read the registered services by scanning tags and identify plugins there
• tells the UI the service endpoints registered in Kong by request

Service should support multi tenancy and able to react to provided tenantid.

sequenceDiagram
    WebUI->>Plugin Registry: asks for the services registered in Kong
    Plugin Registry->>Kong: get the list of plugins by label
    Kong--)Plugin Registry: returns the list of plugins!
    Plugin Registry->>Kong: get the list of services
    Kong--)Plugin Registry: returns the list of services!
    Plugin Registry->>Plugin Registry: Merge into one response
    Plugin Registry--)WebUI: tells the UI the service endpoints 

https://gitlab.eclipse.org/eclipse/xfsc/integration/-/tree/main/manifests/kong?ref_type=heads

https://gitlab.eclipse.org/eclipse/xfsc/integration/-/tree/main/manifests/postgres?ref_type=heads