Add Player.addBankBalance function

[omarcopires]

Pull Request Prelude

• I have followed proper The Forgotten Server code styling.
• I have read and understood the contribution guidelines before making this PR.
• I am aware that this PR may be closed if the above-mentioned criteria are not fulfilled.

Changes Proposed

The function Player.addBankBalance adds a specified amount of money to the player's bank balance. The function takes two parameters: self and amount. The self parameter refers to the player object calling the function and the amount parameter is the amount of money to be added to the player's bank balance.

The function starts by using the setBankBalance method of the player object to set the player's bank balance to the current balance plus the specified amount. This will update the player's bank balance with the added amount.

Example usage:

player:addBankBalance(100)

The addBankMoney function is then called on this player object, with the parameter 100, to add 100 gold coins to the player's bank balance.