elrond-wasm 0.38.0, elrond-codec 0.16.0, mandos 0.18.0

• ContractCall refactor. Building a contract call comes with harder compile-time constraints. This also reduces compiled code size.
• ContractBase supertrait can be now stated explicitly for contract and module traits.
• Debugger:
  • Callback payment is now set correctly.
  • Function names are represented internally as strings instead of bytes, which aids debugging.
• Removed the ei-1-2 feature, which was guarding the newer VM functions. These functions are in the mainnet, so this feature is no longer needed.
• New utility functions: self.send().esdt_local_burn_multi(..., self.blockchain().get_token_attributes(...).
• Updated all crates to Rust 2021.