Extract rust snippets and reference them

snippets/rust/src/static_channel_backup.rs

@@ -0,0 +1,10 @@
+use anyhow::Result;
+use breez_sdk_core::*;
+
+async fn retrieve_backup_files() -> Result<()> {
+    let backup_data = BreezServices::static_backup(StaticBackupRequest {
+        working_dir: "<working directory>".into(),
+    })?;
+
+    Ok(())
+}