Introduce schema/ module

Schema related files are moved there. This excludes schema files that
also interact with mutations, because the mutation module depends on
the schema. Those files will have to go into a separate module.

Closes #12858

db/view/build_progress_virtual_reader.hh

@@ -13,7 +13,7 @@
 #include "readers/flat_mutation_reader_v2.hh"
 #include "mutation/mutation_fragment.hh"
 #include "query-request.hh"
-#include "schema_fwd.hh"
+#include "schema/schema_fwd.hh"
 #include "tracing/tracing.hh"
 
 #include <boost/range/iterator_range.hpp>

db/view/row_locking.hh

@@ -26,7 +26,7 @@
 #include <seastar/core/future.hh>
 
 #include "db/timeout_clock.hh"
-#include "schema_fwd.hh"
+#include "schema/schema_fwd.hh"
 #include "dht/i_partitioner.hh"
 #include "query-request.hh"
 #include "utils/estimated_histogram.hh"

db/view/view.hh

@@ -11,7 +11,7 @@
 #include "dht/i_partitioner.hh"
 #include "gc_clock.hh"
 #include "query-request.hh"
-#include "schema_fwd.hh"
+#include "schema/schema_fwd.hh"
 #include "readers/flat_mutation_reader_v2.hh"
 #include "mutation/frozen_mutation.hh"
 

db/view/view_updating_consumer.hh

@@ -9,7 +9,7 @@
 #pragma once
 
 #include "dht/i_partitioner.hh"
-#include "schema_fwd.hh"
+#include "schema/schema_fwd.hh"
 #include "mutation/mutation_fragment.hh"
 #include "sstables/shared_sstable.hh"
 #include "reader_permit.hh"