converting_mutation_partition_applier: generalize accept_cell to UDTs.
converting_mutation_partition_applier: generalize accept_cell to UDTs.

avikivity/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla