Add CC0 + IP waiver

[Linuks777]

From what I've seen this is practically what AUTOMATIC's philosophy on this project currently is[1], so it'd be simple to finally put the "licensing issue" to rest. Simply merge this PR and all the potential problems (and complaining) vanish, thanks to CC0 freedom no major upheaval will be necessary.

Fixes #2059

[1]

There is no requirement to make this software legally usable. Just clone and use it. If you'd like, you can make an extension with those changes.

Originally posted by @AUTOMATIC1111 in https://github.com/AUTOMATIC1111/stable-diffusion-webui/issues/4222#issuecomment-1303020613