Crypto.com exchange added for backtesting

[gabe777]

Summary

This PR adds support for Crypto.com Spot and Perpetual Futures exchanges, allowing backtesting and candle imports for both. The new options are integrated into the existing Candle Import and Backtesting interfaces.
I needed the exchange for my own backtesting purposes and thought it would be useful to others too.

Changes

• Added new classes to handle API access for both Crypto.com Spot and Perpetual Futures.
• Updated the necessary config and enums to ensure these new exchanges show up as selectable options, without changing the overall behavior of the application.

Testing

• Wrote pytests to cover the new classes in import_candles_mode.

Notes

• I added entries for Crypto.com Exchange in info.py exchange_info. The live_trading option is set to False since I haven't implemented that part, though it would be great to have it. :)
• Regarding the fee attribute, since Crypto.com has a progressive fee structure with different maker/taker rates, I opted to use the highest fee. This way, backtesting results will err on the side of caution (better to show worse performance than better-than-real).