Improve Allen consolidated VELO event model and transform it to be event-based

This MR provides a new Allen consolidated VELO event model:

• It lives under namespace Allen::Views::Velo::Consolidated.
• It provides the classes Hit, Hits, State, States, Track and Tracks.
• Hits, States and Tracks are limited in scope to a single event.
• An object of type Allen::Views::Velo::Consolidated::Tracks is now produced by velo_consolidate_tracks_t, concretely dev_velo_tracks_view_t. It is also provided in the configuration in make_velo_tracks with key dev_velo_tracks_view.
• Two objects of type Allen::Views::Velo::Consolidated::States are produced in velo_kalman_filter_t, concretely dev_velo_kalman_beamline_states_view_t and dev_velo_kalman_endvelo_states_view_t.

These classes and more concretely these objects (dev_velo_tracks_view_t, dev_velo_kalman_beamline_states_view_t and dev_velo_kalman_endvelo_states_view_t) improve the usability and readability of the Allen consolidated Velo Event Model. It does not affect the backend, which remains unmodified.