Host functions for the FxDAO test

[bbyalcinkaya]

This PR implements a set of host functions required to run the FxDAO contract test. The following functions have been added:

1. bytes_new_from_linear_memory
2. bytes_len
3. get_current_contract_address
4. require_auth: Implemented as a no-op function that immediately returns Void, as the authentication system is too complex to be included within the current scope.
5. create_contract: Required for deploying an FxDAO/vaults contract instance from the test contract. Since creating a contract address involves a Sha256 hash function, I've decided to implement this as a cheatcode named kasmer_create_contract, which accepts the new contract's address as a parameter. Once we enable the blockchain plugin for this semantics, we can add create_contract and remove this cheatcode.
6. call: Enables the test contract to call FxDAO/vaults.