Improvements for bdk_bitcoind_rpc::Emitter

* Have separate methods for emitting block vs mempool updates.
* `into_update` (which has been renamed to `into_tx_graph_update`) can
  now filter out irrelevant transactions.
* Update docs.

Add tests:

* `test_sync_local_chain` ensures that `Emitter::emit_block` emits
  blocks in order, even after reorg.
* `test_into_tx_graph` ensures that `into_tx_graph` behaves
  appropriately for both mempool and block updates. It should also
filter txs and map anchors correctly.

crates/bitcoind_rpc/Cargo.toml

@@ -7,5 +7,8 @@ edition = "2021"
 
 [dependencies]
 bdk_chain = { path = "../chain", version = "0.5.0", features = ["serde", "miniscript"] }
-bitcoincore-rpc = { version = "0.16" }
+bitcoincore-rpc = { version = "0.17.0" }
+
+[dev-dependencies]
+bitcoind = { version = "0.32.0", features = ["25_0"] }
 anyhow = { version = "1" }