Fix some gendered emoji

[T0mstone]

People with Bunny ears

These have been changed to be gender-neutral (in Unicode 9.0, according to this).

I also added the gender-specific ZWJ sequences while I was at it, since multi-character symbols are now possible.

Source: https://www.unicode.org/reports/tr51/#multiperson_gender

People holding hands

This is a ZWJ sequence, unlike the other three legacy variants.
I feel like this one only makes sense to also have, now that we can.

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Not sure if we should actually merge this before typst#6489, but it's probably fine since I'm pretty sure that that will land before the next release.

[Enivex]

I feel like we need a more intelligent way to deal with gender and skin color in emojis. It would be a gargantuan task to do manually.

[T0mstone]

For sure, but I came across these while implementing #51 and fixing them like this should be fine for now.

[T0mstone]

Or, well, the bunny fix helps with an issue I came across. The other one is just nice to have anyway and serves as a specific patch since the handholding emoji are quite special in being explicitly gendered whereas most others are now gender-neutral by default.

As an aside, I also noticed how the variants for emoji.handholding are defined with redundant modifiers, but that's also observable via repr, so I didn't wanna change it here.

[knuesel]

This looks like a strict improvement. If we later do something smarter for gendered emojis in a breaking way, that would also break the existing dancing.women.bunnny anyway...