Relax Huggingface login requirement during setup

[ebr]

• Fixes links to the Stable Diffusion weights license agreement. Prints a message about implicit agreement if the user used the --yes flag. Shortens/simplifies messaging and makes the licensing blurb more visible.
• The configuration script will no longer exit if the Huggingface token is not provided. Instead, we show a message about the purpose of the token, with a link to updated documentation, and offer to proceed with the download.
• Always caches the HF token if one is found or provided
• Prints more detailed messaging about where the token was found (or not)
• Validates the token, if exists, by logging in to HuggingFace. Offers an option to re-enter it on failure. This will prevent caching of invalid tokens which are hard for the user to reset.
• Deprecates the --interactive[True] flag and replaces it with --skip-sd-weights[False], because: 1) its real purpose was to avoid token input when downloading the SD weights, which is no longer a blocker, and 2) avoidance of interaction is already achieved with --yes.