[roq-api] Support commissions and fees

[thraneh]

This is tricky for various reasons

• Sometimes we only have OrderUpdate and sometimes we only receive total traded (not partial fills). This implies the OrderUpdate should also track total commissions/fees.
• Sometimes the commissions/fees are only reported by trade and there's no obvious link back to OrderUpdate.
• The commission/fee asset isn't always available and assumptions must be made.
• Sometimes we don't get any commissions/fees at all.

The goal is to fully support when possible.