#127048: [UNI] Emoji sequences with ZERO WIDTH JOINER counted as separate chars when they probably shouldn't

[Samantha McVey]

There is a new roast test, S15-nfg/emoji-test.t

We used to fail 1500+/1943 tests, but now we only fail 275 tests. Will keep 
this open until we are passing all the Emoji tests which contain ZWJ characters