database: Move database, keyspace, table classes to replica/ directory

The database, keyspace, and table classes represent the replica-only
part of the objects after which they are named. Reading from a table
doesn't give you the full data, just the replica's view, and it is not
consistent since reconciliation is applied on the coordinator.

As a first step in acknowledging this, move the related files to
a replica/ subdirectory.

db/view/build_progress_virtual_reader.hh

@@ -19,7 +19,7 @@
  * along with Scylla.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "database.hh"
+#include "replica/database.hh"
 #include "db/system_keyspace.hh"
 #include "db/timeout_clock.hh"
 #include "dht/i_partitioner.hh"

db/view/view.cc

@@ -57,7 +57,7 @@
 #include <seastar/core/coroutine.hh>
 #include <seastar/coroutine/maybe_yield.hh>
 
-#include "database.hh"
+#include "replica/database.hh"
 #include "clustering_bounds_comparator.hh"
 #include "cql3/statements/select_statement.hh"
 #include "cql3/util.hh"

db/view/view_builder.hh

@@ -26,7 +26,7 @@
 #include "service/migration_listener.hh"
 #include "utils/serialized_action.hh"
 #include "utils/UUID.hh"
-#include "database.hh"
+#include "replica/database.hh"
 
 #include <seastar/core/abort_source.hh>
 #include <seastar/core/future.hh>

db/view/view_update_generator.hh

@@ -21,7 +21,7 @@
 
 #pragma once
 
-#include "database.hh"
+#include "replica/database.hh"
 #include "sstables/shared_sstable.hh"
 
 #include <seastar/core/abort_source.hh>