feat(esplora)!: remove EsploraExt::update_local_chain

Previously, we would update the `TxGraph` and `KeychainTxOutIndex`
first, then create a second update for `LocalChain`. This required
locking the receiving structures 3 times (instead of twice, which
is optimal).

This PR eliminates this requirement by making use of the new `query`
method of `CheckPoint`.

Examples are also updated to use the new API.

crates/esplora/src/lib.rs

@@ -16,7 +16,9 @@
 //! [`TxGraph`]: bdk_chain::tx_graph::TxGraph
 //! [`example_esplora`]: https://github.com/bitcoindevkit/bdk/tree/master/example-crates/example_esplora
 
-use bdk_chain::{BlockId, ConfirmationTimeHeightAnchor};
+use std::collections::BTreeMap;
+
+use bdk_chain::{local_chain, BlockId, ConfirmationTimeHeightAnchor, TxGraph};
 use esplora_client::TxStatus;
 
 pub use esplora_client;
@@ -48,3 +50,21 @@ fn anchor_from_status(status: &TxStatus) -> Option<ConfirmationTimeHeightAnchor>
         None
     }
 }
+
+/// Update returns from a full scan.
+pub struct FullScanUpdate<K> {
+    /// The update to apply to the receiving [`LocalChain`](local_chain::LocalChain).
+    pub local_chain: local_chain::Update,
+    /// The update to apply to the receiving [`TxGraph`].
+    pub tx_graph: TxGraph<ConfirmationTimeHeightAnchor>,
+    /// Last active indices for the corresponding keychains (`K`).
+    pub last_active_indices: BTreeMap<K, u32>,
+}
+
+/// Update returned from a sync.
+pub struct SyncUpdate {
+    /// The update to apply to the receiving [`LocalChain`](local_chain::LocalChain).
+    pub local_chain: local_chain::Update,
+    /// The update to apply to the receiving [`TxGraph`].
+    pub tx_graph: TxGraph<ConfirmationTimeHeightAnchor>,
+}