Introduce common classes to access kuksa.val.v1 / kuksa.val.v2 interfaces and DataBrokerSubscriber

[wba2hi]

Is your feature request related to a problem? Please describe.
No

Describe the solution you'd like
Right now kuksa.val.v1 and kuksa.val.v2 were implemented side-by-side with nearly no shared code. We should align this to share a common code base. e.g. there is one DataBrokerConnector which provides access to kuksa.val.v1 / and kuksa.val.v2 apis

Also right now the Subscription mechanism for kuksa.val.v1 is more sophisticated. Instead of opening a new subscription per Path per subscription being done by the user (normal behavior), only the SDK does the Subscription process per Path ONCE and then forwards the events from the SDK to the user. However the DataBrokerSubscriber right now uses kuksa.val.v1 specific models and therefore needs to be changed accordingly before it can be used by kuksa.val.v2

Describe alternatives you've considered
n/a

Additional context
n/a