cql3: expr: rationalize lhs/rhs argument order
cql3: expr: rationalize lhs/rhs argument order

Some functions accept the right-hand-side as the first argument
and the left-hand-side as the second argument. This is now confusing,
but at least safe-ish, as the arguments have different types. It's
going to become dangerous when we switch to expressions for both sides,
so let's rationalize it by always starting with lhs.

Some parameters were annotated with _lhs/_rhs when it was not clear.

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