queen-attack might be missing test cases

[kytrinyx]

See exercism/cpp#42

In some tracks only one diagonal was tested. It could be worth checking other tracks, and perhaps extracting the test cases into a queen-attack.json file.

[IanWhitney]

@kytrinyx, With the standard tests merged I think this one is done!

[kytrinyx]

w00t! Thank you :)