Add RoundOrderSize and RoundOrderPrice

[0xBoringWozniak]

This pull request introduces changes to the hyperliquid/convert.go file, focusing on improving the accuracy of order price and size rounding. The most important changes include adding new rounding functions and modifying existing functions to use these new utilities.

New Functions for Rounding:

• Added RoundOrderSize function to round the order size to the nearest tick size.
• Added RoundOrderPrice function to round the order price to the nearest tick size, considering significant figures and allowed decimals.

Modifications to Existing Functions:

• Modified OrderRequestToWire function to use RoundOrderPrice and RoundOrderSize instead of FloatToWire.
• Modified ModifyOrderRequestToWire function to use RoundOrderPrice and RoundOrderSize instead of FloatToWire.

Reference

ilya-hontarau@696a083