Local server instead of local filesystem

[roxaloxa]

Would be nice if Publii could spin up a basic local web server to preview with so close-to-real environment can be tested. For example, I'm using custom JS in mine to load local files wit fetch() but that doesn't work if the file URL starts with file://. So I just simply can never preview that locally, gotta push it live to test it.

[rgblack316]

Good idea. This is similar to how HUGO does it's previews.