[position] Implement an assert_eq_bitboards! macro

This one helps with printing BitBoards if the assertion fails.

position/src/testing.rs

@@ -36,6 +36,19 @@ macro_rules! formatted_move_list {
     };
 }
 
+#[macro_export]
+macro_rules! assert_eq_bitboards {
+    ($result:expr, $expected:expr) => {{
+        let result = $result;
+        let expected = $expected;
+        assert_eq!(
+            result, expected,
+            "Result:\n{}\nExpected:\n{}",
+            result, expected
+        );
+    }};
+}
+
 pub type TestResult = Result<(), TestError>;
 
 #[derive(Debug, Eq, PartialEq)]