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/connection_handler/block_handler.rs

@@ -235,7 +235,7 @@ where
     }
 }
 
-pub(crate) struct Behaviour<F, G>
+pub(crate) struct BlockBehaviour<F, G>
 where
     F: PrimeField,
     G: CurveGroup<ScalarField = F>,
@@ -246,7 +246,7 @@ where
     events: VecDeque<ToSwarm<DragoonEvent<F, G>, InEvent>>,
 }
 
-impl<F, G> Behaviour<F, G>
+impl<F, G> BlockBehaviour<F, G>
 where
     F: PrimeField,
     G: CurveGroup<ScalarField = F>,
@@ -347,7 +347,7 @@ where
     }
 }
 
-impl<F, G> NetworkBehaviour for Behaviour<F, G>
+impl<F, G> NetworkBehaviour for BlockBehaviour<F, G>
 where
     F: PrimeField,
     G: CurveGroup<ScalarField = F>,