[dtslint] Improve failure message when tests fail on one TS version and pass on another

[marekdedic]

Hi,
I've spent the better part of a day chasing an issue where ExpectType would complain about a type mismatch and then would complain again the other way if I changed the expected type. (#632).

Turns out, the two issues were on different TS versions which output generic types differently (4.9 vs 5.0).

It would be nice if there was a bigger warning when tests pass on one TS version and fail on another (it prints the version in the error message, but apparently, that's not enough) - something like "The test PASS on 5.1 but FAIL on 4.9:"