refactor: split up database/key_value.rs

src/database/key_value/room/mod.rs

@@ -0,0 +1,17 @@
+mod state;
+mod alias;
+mod directory;
+mod edus;
+mod event_handler;
+mod lazy_loading;
+mod metadata;
+mod outlier;
+mod pdu_metadata;
+mod search;
+mod short;
+mod state;
+mod state_accessor;
+mod state_cache;
+mod state_compressor;
+mod timeline;
+mod user;