unqualified emoji ZWJ sequence inconsistencies

[gigamonster256]

Emoji ZWJ sequence behavior on minimally-qualified or unqualified emoji ZWJ sequences are up to the implementor

On macOS, ghostty shows unqualified emoji ZWJ sequences in the same way as their fully-qualified forms (I think this is the coretext layer handling this) but incorrectly reports the width as narrow.

On linux, it seems that ghostty is falling back to different fonts based on whether the emoji ZWJ sequences is qualified or not (missing VS16 in the example case) and also incorrectly reporting the unqualified case as narrow.

See this simplified version of the unicode emoji test for an example