add unfinishedreverie

[Siwat-Keng]

• [x] New artifact package
• [x] Config in artifacts package
• [x] Run pipeline with added config (generates .generated.json files)
• [x] Artifact key
• [x] Shortcuts for artifact key
• [x] Add artifact package to imports
• [x] 2pc
• [x] 4pc
• [x] Update documentation

[srliao]

FYI I didn't check the actual artifact code yet, only commenting on the Burning element part of it