Goal: We need to let people add to PMM additional Services and Nodes for monitoring with types/technologies we don't support for now. 

We also need them to be aligned into default PMM model with Node -> Service model and ability to add Labels (custom and standard)

Expectations: 

• All new objects will be in our Inventory model and structured 

• Dashboards, where we display Nodes "will know" about some "external/remote" Nodes. As well as "External Services" will be presented together with a list on standard services