cql3, related: switch to data_dictionary

Stop using database (and including database.hh) for schema related
purposes and use data_dictionary instead.

data_dictionary::database::real_database() is called from several
places, for these reasons:

 - calling yet-to-be-converted code
 - callers with a legitimate need to access data (e.g. system_keyspace)
   but with the ::database accessor removed from query_processor.
   We'll need to find another way to supply system_keyspace with
   data access.
 - to gain access to the wasm engine for testing whether used
   defined functions compile. We'll have to find another way to
   do this as well.

The change is a straightforward replacement. One case in
modification_statement had to change a capture, but everything else
was just a search-and-replace.

Some files that lost "database.hh" gained "mutation.hh", which they
previously had access to through "database.hh".

db/view/view.cc

@@ -123,7 +123,7 @@ cql3::statements::select_statement& view_info::select_statement() const {
         raw->prepare_keyspace(_schema.ks_name());
         raw->set_bound_variables({});
         cql3::cql_stats ignored;
-        auto prepared = raw->prepare(service::get_local_storage_proxy().get_db().local(), ignored, true);
+        auto prepared = raw->prepare(service::get_local_storage_proxy().data_dictionary(), ignored, true);
         _select_statement = static_pointer_cast<cql3::statements::select_statement>(prepared->statement);
     }
     return *_select_statement;