Remove Neko Target

[Jaduplex]

Addresses #3361

As stated in the original issue that brought this to my attention, Neko is no longer officially supported, and has been deprecated since 2021. Very, very few people use it (or seemingly have in a long time), and it has been all but entirely superseded by Hashlink.

This PR removes the Neko target and all mentions of it.

[DetectiveBaldi]

would like to note that there is probably additional code in related flixel repositories that would probably be affected by this idea it also might be worth labeling the target as deprecated instead of outright removing it (this is mentioned in the linked issue)

[Jaduplex]

would like to note that there is probably additional code in related flixel repositories that would probably be affected by this idea it also might be worth labeling the target as deprecated instead of outright removing it (this is mentioned in the linked issue)

Yeah.