add FF7 Aerith theme

[joyet-simon]

Pull Request Template

Discord username (optional)

If you're in our Discord server, we'd like to give you the Contributor Discord Role, please include your username. Note: It must be labelled like so: username#4747 (make sure to include the #XXXX).

Name of theme

Please include the name of the theme.
FF7 Aerith

How Has This Been Tested?

Have you run the python script? python3 ./scripts/gen_theme_previews.py <folder-name-eg-standard>

Notes

We cannot accept pull request that include custom background images because:

• of licensing restrictions
• we are trying to keep the binary size of the repo as small as possible (just the yaml files)

If your theme has an intended custom background image, include a comment in the yaml with a link to where people should download it.