Update pagination dots to only show dots if needed

[mikeybinns]

Currently, under certain conditions the pagination shows dots when it would make more sense to show a number.
This change updates such an edge case.

Example:
If you have the following variables:
Mid size: 2
End size: 1
Total pages: 5
Current page: 1
Then it will visually output as follows:

Prev 1 2 3 ... 5 Next

Trac ticket: https://core.trac.wordpress.org/ticket/51227

This PR supersedes PR #513 which was very outdated

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Props mikeybinns.

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[github-actions]

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