Info API: OrderFill fields

[0xBoringWozniak]

This pull request includes several changes to the hyperliquid package, focusing on improving error handling, enhancing test coverage, and updating data types for consistency. The most important changes include adding error checks, improving test logging, and converting string fields to float64 in the OrderFill struct.

Error handling improvements:

• hyperliquid/info_test.go: Added a check to ensure TEST_ADDRESS is set in the environment, and panic if it is not.

Test coverage enhancements:

• hyperliquid/info_test.go: Enhanced the TestInfoAPI_GetAccountFills function by adding detailed logging and additional checks for Px, Sz, and Fee fields in the response.

Data type consistency:

• hyperliquid/info_types.go: Updated the OrderFill struct to convert ClosedPnl, Fee, Px, and Sz fields from strings to float64 for better numerical handling.