Refactor AuctionHouseBot.cpp + small bugfix

[PixelWeaver]

Changes Proposed:

• Renaming of the BuyPrice config members into something more meaningful to help with readability
• Refactor in AuctionHouseBot.cpp for readability
• Refactor and bugfix in AuctionHouseBot::Buy (make variable names more meaningful, simplify some if/else, move some checks to a little earlier when relevant, most importantly, properly remove auction from auctionPool: erase takes an iterator argument when you want to delete an element at a specific position, giving it a uint32 will make it look for that value in the set).

Issues Addressed:

• Fixes an issue where the bot sometimes bids several times the above ceiling value.

Tests Performed:

• Builds without error
• Doesn't purchase above the ceiling value anymore

How to Test the Changes:

1. Sell 20 green items with a sell price.
2. For each of them, set the bidding price at exactly the ceiling value minus 1 copper (sell_price_in_copper * 5 - 1), do not put a buyout price.
3. Do this with and without the changes in this branch: with the changes, you'll never have more than the ceiling value, without the changes you'll experience the issue where the bot bids sometimes above twice the ceiling value.