Function get_enum_concrete_variant

pub fn get_enum_concrete_variant(
    db: &dyn SemanticGroup,
    module_id: ModuleId,
    enum_name: &str,
    generic_args: Vec<GenericArgumentId>,
    variant_name: &str,
) -> ConcreteVariant

Gets a ConcreteVariant instance for an enum variant, by module and name. Assumes the variant exists.