Directory Restructure (#1163)

* Move tests -> testing

* Directory restructure

* Update Cargo.toml during restructure

* Update Makefile during restructure

* Fix arbitrary path

crypto/eth2_wallet/src/validator_path.rs

@@ -0,0 +1,41 @@
+use std::fmt;
+use std::iter::Iterator;
+
+pub const PURPOSE: u32 = 12381;
+pub const COIN_TYPE: u32 = 3600;
+
+pub enum KeyType {
+    Voting,
+    Withdrawal,
+}
+
+pub struct ValidatorPath(Vec<u32>);
+
+impl ValidatorPath {
+    pub fn new(index: u32, key_type: KeyType) -> Self {
+        let mut vec = vec![PURPOSE, COIN_TYPE, index, 0];
+
+        match key_type {
+            KeyType::Voting => vec.push(0),
+            KeyType::Withdrawal => {}
+        }
+
+        Self(vec)
+    }
+
+    pub fn iter_nodes(&self) -> impl Iterator<Item = &u32> {
+        self.0.iter()
+    }
+}
+
+impl fmt::Display for ValidatorPath {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "m")?;
+
+        for node in self.iter_nodes() {
+            write!(f, "/{}", node)?;
+        }
+
+        Ok(())
+    }
+}