idl: serialiser: deduplicate vector serialisers
idl: serialiser: deduplicate vector serialisers

In Scylla we have three implementations of vector-like structures
std::vector, utils::chunked_vector and utils::small_vector. Which one is
used is largerly an implementation detail and all should be serialised
by the IDL infrastructure in exactly the same way. To make sure that
it's indeed the case let's make them share the serialiser
implementation.

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