Restructure the Examples Repo

[t-fine]

At the moment this just to get the ball rolling on the more in-depth conversation/vote that must happen in the larger TSC meeting, and attempt to capture some notes/inspiration from the examples working group meetings...

Over the last couple weeks in the Open Horizon Examples Working Group meetings we have been discussing the restructure of the examples repo and what that might look like. The main idea would be to break off the services that are more standalone, and may be used by potential customers outside of learning only, into their own repos.

Hopefully this would have the effect of making the "examples" more consumable so a developer does not need to clone the entirety of the repository if they wanted to just modify the mqtt service, and thus more inclined to contribute.

Restructuring inspiration:
https://github.com/hassio-addons/repository

Two major tasks:

1. New namespace for example (sic), e.g. open-horizon-services
2. Repository for each service