Custom companion shops

[kenedos]

What this PR Implements:

• Custom companion shops that work in a very similar way to merchant shops
• Users can define custom companions and prices in the shop
• Includes a sample implementation: Marina, a companion trader in Klaipeda selling 3 companions (Velhider, Hoglan, and Hawk)
• Companion shop UI includes pagination
• Removes the "Pet Food" table from the companion UI (adds complexity, unecessary)
• Minor fix in dialog close while talking to NPC with shop open that could potentially crash server

What this PR does NOT provide:

• Actual Companion Hiring/Purchase (purchase handler is currently stubbed out). This functionality will be implemented in a separate PR (cough cough Akinue)