test: add support for different state machines
test: add support for different state machines

Current tests uses hash state machine that checks for specific order of
entries application. The order is not always guaranty though.
Backpressure may delay some entires to be submitted and when they are
released together they may be reordered in the debug mode due to
SEASTAR_SHUFFLE_TASK_QUEUE. Introduce an ability for test to choose
state machine type and implement commutative state machine that does
not care about ordering.

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