Studies of $$mathrm B ^*_mathrm s2(5840)^0 $$Bs2∗(5840)0 and $$mathrm B _mathrm s1(5830)^0 $$Bs1(5830)0 mesons including the observation of the $$mathrm B ^*_mathrm s2(5840)^0 ightarrow mathrm B ^0 mathrm K ^0_mathrm S $$Bs2∗(5840)0→B0KS0 decay in proton-proton collisions at $$sqrts=8, ext TeV $$s=8TeV