Add base sets of common configurations

[caspiano]

Is your feature request related to a problem? Please describe.

The default entities are mainly for debugging and testing the environment and are essentially nothing more than placeholders.
They, therefore, haven't much utility for the user.

Describe the solution you'd like

Add useful base sets of common configurations.
These are represented by CSVs defined in PlaceOS/Init.
Add a call to an init task to create the chosen set of examples in placeos start.
These can be controlled by the PLACEOS_EXAMPLES env var as comma-separated strings.

Additional context

• Update default entities init#31