Describe the Issue
Call are CCTX representing a smart contract call without asset
This task is about adding the new type in the CCTX type enum

Issue we will have to think about:

• For revert from ZetaChain to external chains, the assets in the CCTX are used to cover the revert tx fees, if the CCTX doesn't have any asset then revert tx can't be processed.
  We might should want to prevent revert in this case for now.