[core, sql] Tighten packet checks for furnitures

[sruon]

I affirm:

• I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
• I understand I should leave resolving conversations to the LandSandBoat team so that reviewers won't miss what was said.
• I have read and understood the Contributing Guide and the Code of Conduct.
• I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

What does this pull request do?

• Rework item_furnishing table to include each furniture dimensions and how they are supposed to be placed
  • This is all straight from the DATs, credits @atom0s for the infos!
• Reworks the furniture placement packet handler to ensure placements are legitimate
  • Credits @atom0s again for the excellent packet documentation
• Cleans up the furniture removal packet
  • Lots of diff but its mostly because I moved the returns earlier

Steps to test these changes

Place a lot of furnitures and die of boredom