Use [hidden] instead of template in space/divide utilities

[adamwathan]

This PR updates the selectors for the space and divide utilities to be less-Alpine specific and more universally useful by rewriting them like this:

- .space-x-4 > :not(template) ~ :not(template)
+ .space-x-4 > :not([hidden]) ~ :not([hidden])

Now any hidden element will not be considered when deciding which elements to apply the margin/border to. This is still not "perfect" in the sense that it can't account for arbitrary usage of display: none and stuff via CSS, but it is much more universally useful than just looking at template tags.

This is a breaking change for Alpine users but they can get around it by adding hidden to their template tags:

- <template>
+ <template hidden>