MIR: gas consumption of the factorial example.

Answers the following item of %(2023Q3) MIR: prototype:

Implement some gas consumption in Rust that works on the Michelson code of the factorial example.

For context on the factorial example, see #6211 (closed).

Validation: from the MIR prototype it's possible to obtain the gas consumption of a Michelson contract run and there is documentation on how to do so.

This is implemented by !10080 (merged), !10083 (merged) and !10156 (merged).