Directory layout and bootstrapping

Origin data layout

Origin lays out data in files named

data/{keyspace}/{table}-{tableuuid}/la-{generation}-big/{component}.db

One of the keyspaces is the system keyspace, which contains the schema for the other keyspaces (and presumably for itself as well).

To bootstrap, we manually create the schema for the system keyspace (db::system_keyspace::make(database&)) and the read the data from the system keyspace to know about other keyspaces.