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/dragoon_network.rs

@@ -819,6 +819,8 @@ impl DragoonNetwork {
             self.pending_request_block_info
                 .insert(request_id, Sender::SenderMPSC(info_sender.clone()));
         }
+        // ! we never actually get here, need to spawn the request of the list of blocks inside a new task
+        debug!("Finished requesting the file to all providers");
 
         //TODO change this to keep in memory other providers of the same block in case the first one fails (a hash map maybe ?)
         let mut already_request_block = vec![];