Navigator: Start migrating to Conditions Data. 1st allow for "dual-use"

This MR tries to repeat some of the steps we did (@schaffer ) for the Propagator migration to Magnetic field conditions.

As 1st step allow depending on if we pass/fill the conditions Read Handle Key to go either conditions data access or use the svc/ detstore retrieves.

I did not want to alter interfaces as 1st step to keep things minimal per step, but in a later MR we want to pass the EventContext more explict in a few methods (we have that for the methods that depend on propagator calls anyhow)

The default for now is to go to detStore i.e the way things are done in "now" so would not expect output changes. Actually, RunTier0Tests look fine RunTier0Tests.log

In terms of cpu did not see any significant regression and the Tier0 tests etc, but is to be seen. Prb as we move to the ConditionsData there might be some tuning here.

Anyhow let me mention @goetz , @rlangenb , @amorley, @sroe

If CI looks OK with this 0th level changes will take if from there. For sure will do one more for interfaces etc and then we need to start thinking of a "switch over strategy" when we are convinces we are ready.