storage_service: incremental backups
storage_service: incremental backups

Query and set the state of incremental backups. The initial value comes from
the configuration file through the local db reference. Later on, it can be
changed through the interface.

Signed-off-by: Glauber Costa <f8b79557d19b40666ebe336545a0b6178af65685@scylladb.com>

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