Ability to upload multiple images via the image picker

Context

Please see https://www.screencast.com/t/HdFEpiKpr

It is not possible to upload multiple images via an image picker dialogue. You can upload multiple images via clicking 'add image' on an image folder within images (see attached screenshots) but not from an image picker dialogue.

Acceptance criteria

1. Users can select and upload multiple image files via the image-picker flow.