#5160 feat/allow fees in different tokens

In this PR we introduce the required changes for the client to accept having fees for a trade in different tokens (something that happens with Binance connector, that sometimes can charge fees in BNB and sometimes in the trade quote token).

The changes include:

• Remove fee_amount and fee_token from the order complete events, since that information was not being used anywhere
• Change PNL calculation logic to convert fees in different tokens to the quote token using the RateOracle as price provider
• Modification of the start command to always start also the RateOracle, for it to regularly update prices

Link: https://github.com/hummingbot/hummingbot/pull/5160