Move LArHitFilter to a separate package which can be included in the AthSimulation project

Move the enum used in LArHitFilter and LArHitMerger to the LArSimEvent package. The enum used in the LArHitFilter and LArHitMerger algorithms was part of the LArHitEMap class, even though it was not used by any clients of LArHitEMap and the two algorithms did not otherwise use LArHitEmap.

This allow the LArHitFilter algorithm to be moved into a new LArHitAlgs package which can then be added to the AthSimulation project allowing the FilterHit_tf.py transform to be run using the AthSimulation project.