Merge branch 'cherry-pick-457bdc2b' into 'Sim09-upgrade' (Markov chain beam spot LHCBGAUSS-906)
LHCBGAUSS-906 Add BeamSpotMarkovChainSampleVertex
Picked from master MR !36 (merged) to Sim09 upgrade branch.
See merge request !37 (merged)
LHCBGAUSS-906 Add BeamSpotMarkovChainSampleVertex
Picked from master MR !36 (merged) to Sim09 upgrade branch.
See merge request !37 (merged)