TL;DR

Added balance aggregation support for token balances API endpoint and simplified response model

What changed?

• Modified token balance query to support aggregated balances with GROUP BY functionality
• Simplified BalanceModel response by removing redundant fields (chainId, tokenType, owner)
• Added serialization functions to transform token balances into the response model
• Updated Swagger documentation for the balance endpoint path
• Added support for custom column selection in token balance queries
• Implemented conditional balance filtering based on aggregation status

Why make this change?

To provide more efficient token balance querying by allowing balance aggregation and reducing redundant data in the response. This improves API performance and simplifies the response structure for consumers.