transport/server: Explict CQL type IDs
transport/server: Explict CQL type IDs

The CQL type IDs are specified as hex in the CQL binary protocol
specification. Define CQL type IDs in the code explicitly to make
reviewing the code and adding new types easier.

Message-Id: <2db01d18d48639693aae6f624bef5efaf4f756e5@scylladb.com>

scylladb/scylla,avikivity/scylla,duarten/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla,scylladb/scylla,avikivity/scylla,raphaelsc/scylla,raphaelsc/scylla,raphaelsc/scylla,duarten/scylla