Add Images with different file formats

[Morsey187]

Issue: #457

Description

Images used within the initial data (populated via load_initial_data) only contain file formats jpg or jpeg, this PR aims to add additonal formats to help with testing as described in #457.

I've aimed to add new images in each individual commit to help with reviewing as well as updating images specific to ones that appear under the “blog” section on the Home page, which should make for easier testing.

Testing notes

I’d recommened flushing your database and setting up the project from scratch using load_intial_data, then reviewing the site and page editor.

Notes

• I think SVG support should be added in a seperate PR, keen to keep discussions in relation to this in the original Issue.

[Morsey187]

Issue:

1. The site has a 10.0 MB upload restriction, although likely sensible, finding a lightweight copyright free giff (or video we can convert to a giff) is surprisingly difficult. I found this one here https://pixabay.com/videos/bread-cut-slice-preparation-starch-209418/ and had to shorten and compress the giff multiple times to get it under the 10.0mb limit.
2. The giff is compressed down to a bad quality and arguably rather confusing contextually (it's on the "The Greatest Thing Since Sliced Bread" page).