Add redis caching to getting user notifications and projects [MOD-540] (#723)

* Add redis caching to getting a user's project ids

* Run `cargo sqlx prepare` to update the sqlx-data.json

* Add redis caching for getting user notifications

* Fix new clippy warnings

* Remove log that shouldn't have been committed

* Batch insert of notifications (untested)

* sqlx prepare...

* Fix merge conflict things and use new redis struct

* Fix bug with calling delete_many without any elements (caught by tests)

* cargo sqlx prepare

* Add tests around cache invalidation (and fix bug they caught!)

* Some test reorg based on code review suggestions

src/database/models/image_item.rs

@@ -236,12 +236,7 @@ impl Image {
 
             for image in db_images {
                 redis
-                    .set(
-                        IMAGES_NAMESPACE,
-                        image.id.0,
-                        serde_json::to_string(&image)?,
-                        None,
-                    )
+                    .set_serialized_to_json(IMAGES_NAMESPACE, image.id.0, &image, None)
                     .await?;
                 found_images.push(image);
             }