Add bulk one_time_keys adder to interface.

Add device_exists to interface.

Signed-off-by: Jason Volk <jason@zemos.net>

src/service/users/device.rs

@@ -391,6 +391,14 @@ pub async fn get_device_metadata(
 		.deserialized()
 }
 
+#[implement(super::Service)]
+pub async fn device_exists(&self, user_id: &UserId, device_id: &DeviceId) -> bool {
+	self.db
+		.userdeviceid_metadata
+		.contains(&(user_id, device_id))
+		.await
+}
+
 #[implement(super::Service)]
 pub async fn get_devicelist_version(&self, user_id: &UserId) -> Result<u64> {
 	self.db