chore: rename amountOwed -> amountIn

...for consistency.

Also remove comment. We will keep exact_out to avoid future interface changes.

src/encoding/models.rs

@@ -65,7 +65,6 @@ pub struct Transaction {
 #[allow(dead_code)]
 pub struct EncodingContext {
     pub receiver: Bytes,
-    // TODO should we keep this?
     pub exact_out: bool,
     pub router_address: Bytes,
 }