refactor: split up database/key_value.rs

src/database/key_value/mod.rs

src/database/key_value/room.rs

src/database/key_value/room/alias.rs

src/database/key_value/room/directory.rs

src/database/key_value/room/edus/presence.rs

src/database/key_value/room/edus/read_receipt.rs

src/database/key_value/room/edus/typing.rs

src/database/key_value/room/lazy_load.rs

src/database/key_value/room/metadata.rs

src/database/key_value/room/mod.rs

src/database/key_value/room/outlier.rs

src/database/key_value/room/pdu_metadata.rs

src/database/key_value/room/state.rs