Write `get-file` and commands to get the list of blocks from another node

Description

This closes #1 (closed) by providing an API that allows to get a file with just its hash

Detailed list of changes

• add get_file, get_blocks_info_from and other things related to managing the filesystem
• add new commands to nu API
• remove DragoonBehaviour as it was not useful
• add two new tests for get_file and change the already existing test to use the new API

Note

The get_file is still very rough, the error management needs to be handled better to take into a lot more cases of failure

src/main.rs

@@ -72,7 +72,8 @@ pub(crate) async fn main() -> Result<(), Box<dyn Error>> {
             "/encode-file/:file_path/:replace-blocks/:encoding-method/:encode_mat_k/:encode_mat_n/:powers_path",
             get(commands::create_cmd_encode_file),
         )
-        .route("/get-block-from/:peer_id_base_58/:file_hash/:block_hash", get(commands::create_cmd_get_block_from));
+        .route("/get-block-from/:peer_id_base_58/:file_hash/:block_hash", get(commands::create_cmd_get_block_from))
+        .route("/get-file/:file_hash", get(commands::create_cmd_get_file));
 
     let router = router.with_state(Arc::new(app::AppState::new(cmd_sender)));