feat: update wallet::Balance to use bitcoin::Amount

- update all fields `immature`, ` trusted_pending`, `unstrusted_pending`
  and `confirmed` to use the `bitcoin::Amount` instead of `u64`
- update all `impl Balance` methods to use `bitcoin::Amount`
- update all tests that relies on `keychain::Balance`

crates/chain/src/keychain.rs

@@ -14,6 +14,7 @@ use crate::{collections::BTreeMap, Append};
 
 #[cfg(feature = "miniscript")]
 mod txout_index;
+use bitcoin::Amount;
 #[cfg(feature = "miniscript")]
 pub use txout_index::*;
 
@@ -90,13 +91,13 @@ impl<K> AsRef<BTreeMap<K, u32>> for ChangeSet<K> {
 )]
 pub struct Balance {
     /// All coinbase outputs not yet matured
-    pub immature: u64,
+    pub immature: Amount,
     /// Unconfirmed UTXOs generated by a wallet tx
-    pub trusted_pending: u64,
+    pub trusted_pending: Amount,
     /// Unconfirmed UTXOs received from an external wallet
-    pub untrusted_pending: u64,
+    pub untrusted_pending: Amount,
     /// Confirmed and immediately spendable balance
-    pub confirmed: u64,
+    pub confirmed: Amount,
 }
 
 impl Balance {
@@ -104,12 +105,12 @@ impl Balance {
     ///
     /// This is the balance you can spend right now that shouldn't get cancelled via another party
     /// double spending it.
-    pub fn trusted_spendable(&self) -> u64 {
+    pub fn trusted_spendable(&self) -> Amount {
         self.confirmed + self.trusted_pending
     }
 
     /// Get the whole balance visible to the wallet.
-    pub fn total(&self) -> u64 {
+    pub fn total(&self) -> Amount {
         self.confirmed + self.trusted_pending + self.untrusted_pending + self.immature
     }
 }