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

@@ -4,6 +4,7 @@ mod dragoon;
 mod dragoon_network;
 mod error;
 mod to_serialize;
+mod peer_block_info;
 
 use axum::routing::get;
 use axum::Router;