Generalized hip-756 with scheduleContractCall

[littletarzan]

HIP-756 introduced the idea of scheduling a contract call using Hedera Schedule Service for the purpose of modifying token entities. However, it's possible to do much more than this by allowing generalized contract calls to be scheduled by HSS. Fundamentally, contract calls consist of a 4 byte function selector and a series of encoded bytes that can be passed to a smart contract using HSS.

HIP-756 can be generalized in the form of a scheduleContractCall(bytes calldata data) HTS precompile. This would minimize the size of IHederaTokenService.sol and allow smart contract developers maximum freedom for contract calls they can schedule.