Add benchmarking for FilesystemStore

We re-add benchmarking for `FilesystemStore` now that we switched over
to it.

bench/benches/bench.rs

@@ -15,6 +15,7 @@ criterion_group!(benches,
 	lightning::routing::router::benches::generate_large_mpp_routes_with_probabilistic_scorer,
 	lightning::sign::benches::bench_get_secure_random_bytes,
 	lightning::ln::channelmanager::bench::bench_sends,
+	lightning_persister::fs_store::bench::bench_sends,
 	lightning_rapid_gossip_sync::bench::bench_reading_full_graph_from_file,
 	lightning::routing::gossip::benches::read_network_graph,
 	lightning::routing::gossip::benches::write_network_graph);

lightning-persister/src/fs_store.rs

@@ -515,3 +515,17 @@ mod tests {
 		added_monitors.clear();
 	}
 }
+
+#[cfg(ldk_bench)]
+/// Benches
+pub mod bench {
+	use criterion::Criterion;
+
+	/// Bench!
+	pub fn bench_sends(bench: &mut Criterion) {
+		let store_a = super::FilesystemStore::new("bench_filesystem_store_a".into());
+		let store_b = super::FilesystemStore::new("bench_filesystem_store_b".into());
+		lightning::ln::channelmanager::bench::bench_two_sends(
+			bench, "bench_filesystem_persisted_sends", store_a, store_b);
+	}
+}