Add diffusionkit to local-apps

[ardaatahan]

Opening this PR as per @Vaibhavs10's suggestion here regarding DiffusionKit LocalApps integration.

This PR:

1. Adds diffusionkit to the LOCAL_APPS object in local-apps.ts.
2. Adds snippetDiffusionKit function that generates the snippet string for diffusionkit in the same file.

[Vaibhavs10]

Thanks a lot for opening this PR and sorry for the delay. Conceptually approving the PR as the snippet looks good to me.

Will let @enzostvs chime in about what else is needed w.r.t to showing the snippet for the Local App itself.

Note: Please make sure to run the linter to make the linter tests pass.

[enzostvs]

Hi @ardaatahan,
Thanks for adding DiffusionKit as a new Local App!

I'll need your logo in .SVG format please 🙏

[julien-c]

if binary is always the same mayber simpler to hardcode it a const command = string

[julien-c]

let's maybe wait till the binary is packaged w/o pip for us to ship this one (as it's a bit redundant with the model-library, imo)

[julien-c]

(also cc @Wauplin given #869 (review))

[Vaibhavs10]

Just to summarise discussions on next steps w/ @ZachNagengast @atiorh

Argmax will put DiffusionKit over on brew and we'll update snippets accordingly.