Update ALLOWED_ORIGINS to match dev requirements (#393)

## What's changed?

When running the Editor frontend using the web component (on
localhost:3012 as per the README / `.env` config) I received CORS
errors, this PR provides the necessary updates to the config for
development (ie. adds `localhost:3012`), along with listing the hosts /
ports in an ascending order.

.env.example

@@ -1,4 +1,4 @@
-ALLOWED_ORIGINS=localhost:3000,localhost:3002,localhost:3010,editor.rpfdev.com,localhost:3009
+ALLOWED_ORIGINS=localhost:3000,localhost:3002,localhost:3009,localhost:3010,localhost:3012,editor.rpfdev.com
 
 AWS_ACCESS_KEY_ID=changeme
 AWS_S3_ACTIVE_STORAGE_BUCKET=changeme