Consider removing `ZetaFees` from CCTX object

[lumtis]

Describe the Issue This value doesn't seem to have any utility. It is not read in the protocol, and is only used for Zeta transfers, bringing some inconsistency in the CCTX objects.

I think we should remove this value completely. Consider using a TotalFees paid, or keeping the initial amount in the CCTX object if a client wants to calculate the fees paid