tools/vm: Enhance Callable Opcodes

[marioevz]

Makes Op opcodes callable and the resulting bytecode automatically sets the stack up.

If the opcode has data portion, the first argument is required and it becomes the data that is appended after the opcode.

The rest of the arguments are considered the stack, and they are appended before opcode byte, in LIFO order (the last argument is pushed first to the stack, and the first argument is pushed last).

E.g.

Op.SSTORE(
             -1,
             Op.CALL(
                 Op.GAS,
                 Op.ADDRESS,
                 Op.PUSH1(0x20),
                 0,
                 0,
                 0x20,
                 0x1234,
             ),
         ),

In this example, the Op.SSTORE saves the result of the Op.CALL into the 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff key of the storage, and the parameters of Op.CALL are pushed into the stack before its execution (0x1234 is pushed first to the stack using an implicit Op.PUSH2, then 0x20 using Op.PUSH1, and so on until Op.GAS).

[spencer-tb]

Really nice! No more Opcode mistakes now (hopefully) 👍