Add embedded ctx operations to map_eqc

Fix riak_dt_orswot bug found by same


    OK, passed 1000000 tests

    17.45167% {map_eqc,ctx_update,5}
    17.44523% {map_eqc,update,4}
    17.41366% {map_eqc,add,4}
    13.68039% {map_eqc,replicate,3}
    10.01635% {map_eqc,make_ring,2}
    9.51253% {map_eqc,remove,2}
    8.34556% {map_eqc,ctx_remove,4}
    6.13462% {map_eqc,set_n,1}
    true