Resolve "Image element file uploads aren't displaying properly."

What is in this MR

This MR ensures that when an ImageElement is given an uploaded file, it displays it properly. At the moment it only renders image_url images.

How to test this MR

Create three ImageElement in your page:

1. An ImageElement with an uploaded file, and text as its alt.
2. An ImageElement with a text image URL, and text as its alt.
3. An ImageElement with a formula image URL, and a formula as its alt.

Confirm all three permutations are working correctly.

Merge Request Checklist

• changelog.md has been updated if required.
• New/updated Premium/Enterprise features are separated correctly in the premium or enterprise folder
• The latest Chrome and Firefox have been used to test any new frontend features
• Documentation has been updated
• Quality Standards are met
• Performance: tables are still fast with 100k+ rows, 100+ field tables
• The redoc API pages have been updated for any REST API changes
• Our custom API docs are updated for changes to endpoints accessed via api tokens
• The UI/UX has been updated following UI Style Guide

Closes #2253 (closed)