Introduce Token module wasm host

[limemloh]

Introduce a new wasm host type for running the upcoming Token modules, with some similarities to smart contracts.

A token module will export several functions:

• holder_operation return status code.
• governance_operation return status code.
• Arbitrary read-only functions for reading the state.

The host functions should be:

• Mint
  • Mint some amount of tokens to the provided account, and log an event.
  • Arguments: account, amount, memo
• Burn
  • Burn some amount of tokens from the given account, and log an event.
  • Arguments: account, amount, memo
  • Return: success or failure
• Transfer
  • This will immediately transfer funds from one account to another account and log event.
  • Arguments: sender, receiver, amount, memo
  • Callable from both holder_operation and token_governance
• Query account balance
  • Get the balance of a specific account.
• State functions
  • TBD
• Log custom event
  • Arguments: event (bytes)
• Spend energy
  • Arguments: energy amount
  • Aborts transaction if insufficient available, rolling back the state mutations