Version Track object, revert changes in TDR

• Add inline namespace v1 to Track.xml renamed to Track_v1.xml.

• Add additional namespace Event, so that the full namespace is LHCb::Event::v1::Track(backwards compatible).

• Add Track.h in TrackEvent/TrackEvent/ which includes Track_v1.h.

• Forward declarations in many places need to be changed to include "Event/Track.h".

• Reverts the change of vector<State*> to vector<State> done in the former TDR branch. Keeps the removal of the clone and cloneWithKey.

Addresses #7 (comment 1755867)

Replaces !1424 (closed)

Will be followed up by adding back the TDR Track as v2::Track.