feat: Implement Live Preview

[FoxxMD]

This PR supersedes #234 -- it is functionally the same work @sebaxakerhtc and I already did but has been rebased on top of 1b17f175cbf10786dfb404c31645928a5d8dd1a5 and has all of the minor/cleanup commits squashed into major changes. Additional changes not in #234:

• Uses job presence for end-of-generation detection
• Handles progress without image previews (fixes https://github.com/Kilvoctu/aiyabot/pull/234#issuecomment-1973777209 IE https://github.com/sebaxakerhtc/Marusya-bot-for-auto111/pull/11#issuecomment-1973768299)
• Implements live_preview per-channel setting

[Kilvoctu]

Thank y'all for your support and work 💖