B+ -> DarkBoson ( -> pi+pi- or K+K-) K+ with lab rapidity cut

See merge request !1330

(cherry picked from commit f7f68bef)

9778038b Added dec files with Dark Scalar Boson decay into pi+pi- and K+K- with the aim...
ae401401 Update Bu_KDarkBoson2PiPi,m=2500MeV,t=400ps,TightCut.dec
583c499a Changed EventType for both files
6665c3cf Update Bu_KDarkBoson2KK,m=2500MeV,t=400ps,TightCut.dec
7eef50f1 Changed Dark Boson mass due to channels decay probability
6a26edf5 Update Bu_KDarkBoson2PiPi,m=1000MeV,t=400ps,TightCut.dec