Allow external image src

[refact0r]

I have set the media_folder setting to a folder within the /src folder of my Sveltekit site, as I want to use vite-imagetools to transform and optimize all images. This means that the images would not be available through a direct path like they would in /static, and so their thumbnails don't show up in Sveltia's image library. Thus I would like to see external image urls being allowed for the public_folder setting. Maybe it would be even better to have a separate option for the path of Sveltia's image thumbnails vs the path written into the markdown files.

[kyoshino]

Hey, thanks for filing the issue! Yeah, I know there are some cases image previews don’t work. The site mentioned in #6 has the same issue with vite-imagetools. I’ll figure out how to work around it soonish.

[refact0r]

It seems like having images in /static and importing from there works somehow, but Sveltekit really doesn't like it and gives constant console warnings.

[kyoshino]

I have fixed the issue indirectly in 6ba93d6 now shipped as v0.5.3. Just like Netlify CMS, the preview files will now be loaded from GitHub through the API, not from the production site, so the paths are no longer an issue.