feat(chain)!: Implement ConfirmationBlockTime

Both `bdk_electrum` and `bdk_esplora` now report the exact block
that the transaction is in, which removes the need for having the
old `ConfirmationTimeHeightAnchor` and `ConfirmationHeightAnchor`.
This PR introduces a new, simpler anchor type that can be modified
to support additional data in the future.

example-crates/example_bitcoind_rpc_polling/src/main.rs

@@ -16,7 +16,7 @@ use bdk_chain::{
     indexed_tx_graph,
     indexer::keychain_txout,
     local_chain::{self, LocalChain},
-    ConfirmationTimeHeightAnchor, IndexedTxGraph, Merge,
+    ConfirmationBlockTime, IndexedTxGraph, Merge,
 };
 use example_cli::{
     anyhow,
@@ -38,7 +38,7 @@ const DB_COMMIT_DELAY: Duration = Duration::from_secs(60);
 
 type ChangeSet = (
     local_chain::ChangeSet,
-    indexed_tx_graph::ChangeSet<ConfirmationTimeHeightAnchor, keychain_txout::ChangeSet<Keychain>>,
+    indexed_tx_graph::ChangeSet<ConfirmationBlockTime, keychain_txout::ChangeSet<Keychain>>,
 );
 
 #[derive(Debug)]