Disallow ksorting lists

[danog]

Fixes #7018.
Settled on the same logic used for array_values, as lists can only be constructed by appending elements to an array or by using array_values itself, in both cases they are sorted by default.

[orklah]

I'm not a fan of this one, ksort is hardly a function to transform types, so RedundantCast feels very weird here... However, I couldn't find a more adapted issue and I'm not sure this case is common enough to create a new issue...

[weirdan]

I'd suggest to add RedundantFunctionCall for this kind of issues. Also, this looks very useful to me (as are other dead/useless code checks).

[orklah]

I was not clear, I meant that I was not a fan of this being classified as RedundantCast but the feature seem fine though.

I'm okay with a RedundantFunctionCall, thinking about it more, this could indeed be reused (a dumb example, but a call to max() with a single value could fit in there).

[danog]

Done!

[orklah]

Cool! Thanks!

[orklah]

@weirdan Can I let you merge that and updating the baseline for phpunit?

[weirdan]

Thanks!