message: Add tests for // and %
  Summary: Based on the Starlark spec, and using Python to validate. The code behind % in particular looks a bit suspicious, but is in fact correct.
diff: @@ -680,6 +680,13 @@ pub trait StarlarkValue<'v>: 'v + AnyLifetime<'v> + Debug + Display {
  /// ```rust
  /// # starlark::assert::all_true(r#"
  /// 5 % 3 == 2
  + /// -5 % -3 == -2
  + /// 5 % -3 == -1
  + /// -5 % 3 == 1
  + /// 5.5 % 3.0 == 2.5
  + /// -5.5 % 3.0 == 0.5
  + /// 5.5 % -3.0 == -0.5
  + /// -5.5 % -3.0 == -2.5
  /// "a %s c" % 3 == "a 3 c"
  /// "Hello %s, your score is %d" % ("Bob", 75) == "Hello Bob, your score is 75"
  /// "%d %o %x" % (65, 65, 65) == "65 101 41"
  @@ -701,6 +708,13 @@ pub trait StarlarkValue<'v>: 'v + AnyLifetime<'v> + Debug + Display {
  /// ```rust
  /// # starlark::assert::all_true(r#"
  /// 7 // 2 == 3
  + /// -7 // -2 == 3
  + /// 7 // -2 == -4
  + /// -7 // 2 == -4
  + /// 7.0 // 2.0 == 3.0
  + /// -7.0 // -2.0 == 3.0
  + /// 7.0 // -2.0 == -4.0
  + /// -7.0 // 2.0 == -4.0
  /// 3.0 // 2.0 == 1.0
  /// # "#);
  /// ```
  