Provide a way to serialize/deserialize Base<Resource> field

[StatisMike]

A method for serde to receive the Base<Resource> field after deserialization

#[derive(GodotClass, Serialize, Deserialize, GdProp)]
#[class(init,base=Resource)]
pub struct TestResource {
    set: HashSet<InnerThing>,
    vec: Vec<InnerThing>,
    #[serde(with="gd_props::serde_gd::base")]
    base: Base<Resource>
}

Or separate derive macro GdPropWithBase

#[derive(GodotClass, Serialize, Deserialize, GdPropWithBase)]
#[class(init,base=Resource)]
pub struct TestResource {
    set: HashSet<InnerThing>,
    vec: Vec<InnerThing>,
    #[serde(with="gd_props::serde_gd::base")]
    base: Base<Resource>
}