message: [pdsl_core] Add storage::HashMap::contains_key method
diff: @@ -334,6 +334,18 @@ where
  }
  }
  + /// Returns `true` if there is an entry corresponding to the key in the map.
  + pub fn contains_key<Q>(&self, key: &Q) -> bool
  + where
  + K: Borrow<Q>,
  + Q: HashAsKeccak256 + Eq + ?Sized,
  + {
  + match self.get(key) {
  + Some(_) => true,
  + None => false,
  + }
  + }
  +
  /// Returns the entry corresponding to the key.
  ///
  /// The key may be any borrowed form of the map's key type,
  