Add protobuf services for various entities

[ivucica]

Add a new protobuf file proto/tibiawiki.proto implementing gRPC services for various entities.

• Define the Book service with GetBook and ListBooks methods using google.api.http annotations.
• Define the Building service with GetBuilding and ListBuildings methods using google.api.http annotations.
• Define the Corpse service with GetCorpse and ListCorpses methods using google.api.http annotations.
• Define the Creature service with GetCreature and ListCreatures methods using google.api.http annotations.
• Define the Effect service with GetEffect and ListEffects methods using google.api.http annotations.
• Define the HuntingPlace service with GetHuntingPlace and ListHuntingPlaces methods using google.api.http annotations.
• Define the Item service with GetItem and ListItems methods using google.api.http annotations.
• Define the Key service with GetKey and ListKeys methods using google.api.http annotations.
• Define the Location service with GetLocation and ListLocations methods using google.api.http annotations.
• Define the LootStatistic service with GetLootStatistic and ListLootStatistics methods using google.api.http annotations.
• Define the Missile service with GetMissile and ListMissiles methods using google.api.http annotations.
• Define the Mount service with GetMount and ListMounts methods using google.api.http annotations.
• Define the NPC service with GetNPC and ListNPCs methods using google.api.http annotations.
• Define the Object service with GetObject and ListObjects methods using google.api.http annotations.
• Define the Outfit service with GetOutfit and ListOutfits methods using google.api.http annotations.
• Define the Quest service with GetQuest and ListQuests methods using google.api.http annotations.
• Define the Spell service with GetSpell and ListSpells methods using google.api.http annotations.
• Define the Street service with GetStreet and ListStreets methods using google.api.http annotations.
• Add docstrings to services and methods.

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For more details, open the Copilot Workspace session.

[ivucica]

Note, this was experimental and not intended to end up as an actual visible PR. While it would be just cool to have a protobuf definition, I actually intend to drop this PR.