(Re-)implement specific validation checks after JSON Schema switch

[alex4401]

• v0.17:
• • [x] Ensure group from association string exists
• • [x] Ensure no overlap between group and category IDs
• • [x] Ensure no overlap between marker IDs
• • [x] Ensure no duplicates in an association string
• • [x] Ensure fragment references are valid
• • [x] Emit errors if file references are invalid
• • [x] Emit depreciation warnings
• • [x] Emit a warning if autoNumberInChecklist is set when isCollectible is false
• v0.17.2:
• • [x] Check zoom.min is lower than zoom.max
• v0.17.4:
• • [ ] Ensure searchKeywords is not specified when canSearchFor is false
• • [ ] Emit a warning if searchKeywords or canSearchFor is specified when marker search is disabled
• • [ ] Emit a warning if a marker's article matches its group's shared value
• • [ ] Emit an error if isWikitext is set without name or description