feat: Impl fmt::Display for canonical Error

[bvrooman]

Progress towards upgrading fuel-vm inside fuel-core:

This PR adds fmt::Display to canonical::Error. This is helpful because it allows canonical::Error to be used seamlessly in places where it is replacing std::io::Error. Specific areas include:

    async fn estimate_predicates(
        &self,
        ctx: &Context<'_>,
        tx: HexString,
    ) -> async_graphql::Result<Transaction> {
        let mut tx = FuelTx::from_bytes(&tx.0)?;
        ...

This example requires that the possible error returned by from_bytes(..) implements Display. Without this implementation, the code will fail to compile.

With this change, the upgrade branch compiles locally without error or warning.