`Resource` should implement `Display`

[tdelabro]

#[derive(
    Clone, Copy, Debug, Deserialize, EnumIter, Eq, Hash, Ord, PartialEq, PartialOrd, Serialize,
)]
#[cfg_attr(
    feature = "parity-scale-codec",
    derive(parity_scale_codec::Encode, parity_scale_codec::Decode)
)]
#[cfg_attr(feature = "scale-info", derive(scale_info::TypeInfo))]
pub enum Resource {
    #[serde(rename = "L1_GAS")]
    L1Gas,
    #[serde(rename = "L2_GAS")]
    L2Gas,
}

The string "L1_GAS" and "L2_GAS" are defined by the protocol. Right now I have to define those myself while using this lib:

const L1_GAS: &[u8] = b"L1_GAS";
const L2_GAS: &[u8] = b"L2_GAS";

...

match resource {
        Resource::L1Gas => L1_GAS,
        Resource::L2Gas => L2_GAS,
    } 

This is error prove and unnecessary. starknet-api should provide a way for the lib consumers to access those values directly.
Display provides the to_string method, which seems like a good way to implement this. It could also be used in your serde(rename) tag, instead of hardcoding it.