Add tryfrom for Lookups

src/main.rs

@@ -85,21 +85,8 @@ fn main() -> Result<(), Box<dyn Error>> {
         } => {
             inputs = inp;
 
-            let output_plan = if let Some(plan) = plan {
-                Ok(ynab::Lookup::Name(plan))
-            } else if let Some(plan_id) = plan_id {
-                Ok(ynab::Lookup::Id(plan_id))
-            } else {
-                Err("no plan name or id".to_string())
-            }?;
-
-            let output_account = if let Some(account) = account {
-                Ok(ynab::Lookup::Name(account))
-            } else if let Some(account_id) = account_id {
-                Ok(ynab::Lookup::Id(account_id))
-            } else {
-                Err("no account name or id".to_string())
-            }?;
+            let output_plan = ynab::Lookup::try_from((plan, plan_id))?;
+            let output_account = ynab::Lookup::try_from((account, account_id))?;
 
             Output::Ynab {
                 token,