MIR: add support for multisig's instructions/types/values

Let's add support for the following instructions + types (and respective values):

• SELF, contract
• ADDRESS, address
• CHAIN_ID, chain_id
• PACK, bytes
• UNPAIR
• ITER (list overload)
• IF_LEFT, or
• IF_CONS
• CONS
• CHECK_SIGNATURE, key, signature, bytes
• TRANSFER_TOKENS, contract
• SET_DELEGATE, key_hash