Use signed amount in gettransaction

We mistakenly used an `Amount` when the amount type returned by
`gettransaction` can be negative.

Use `SignedAmount` instead of `Amount`.

Author: tcharding

types/src/model/wallet.rs

@@ -277,7 +277,7 @@ pub struct GetReceivedByAddress(pub Amount);
 pub struct GetTransaction {
     /// The transaction amount.
     #[serde(default, with = "bitcoin::amount::serde::as_btc")]
-    pub amount: Amount,
+    pub amount: SignedAmount,
     /// The amount of the fee.
     ///
     /// This is negative and only available for the 'send' category of transactions.

types/src/v17/wallet/into.rs

@@ -325,7 +325,7 @@ impl GetTransaction {
     pub fn into_model(self) -> Result<model::GetTransaction, GetTransactionError> {
         use GetTransactionError as E;
 
-        let amount = Amount::from_btc(self.amount).map_err(E::Amount)?;
+        let amount = SignedAmount::from_btc(self.amount).map_err(E::Amount)?;
         let fee = self.fee.map(|fee| SignedAmount::from_btc(fee).map_err(E::Fee)).transpose()?;
 
         let block_hash =