fix(Pagination): handle unknown totalItems again

[finken2]

Closes #16298

a previous PR broke the ability to use pagesUnknown and totalItems. This fixes that and these things:

• next page button no longer gets disabled
• don't render the Select for page selection when pagesUnknown. (it previously rendered and did nothing)
• Fix text for "page x" when pagesUnknown
• Adds some margin next to that text so it looks better
• Add a story for pagesUnknown and totalItems undefined
• Simplify some of the logic where there were unneeded ternaries and double checks

Changelog

Changed

• Pagination: revert previous change that defaulted totalItems to 1
• Pagination: don't render non-functional page dropdown when pagesUnknown

Testing / Reviewing

New story in storybook
unit test added
send totalItems undefined

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[tay1orjones]

This is a really solid improvement, thanks for tackling it! I'm not sure why we didn't do something like this earlier. Your solution here is much better than what I was previously recommending in #9754

I do think a better long-term alternative to not rendering the select would be a number input, #5546

[alisonjoseph]

Nice!