feat(tooltip): add alignment utility classes (start, center, end)

[pdanpdan]

• apply to all positions (top, bottom, left, right)
• add a new variable --tt-tail-off to set offset of the tail for start and end alignment

example: https://play.tailwindcss.com/Qt8vZTMlSe?file=css

close #4229

[saadeghi]

Thanks for the PR @pdanpdan
There's a concern about the new class names.
The existing class names for left and right were bad ideas, because ideally tooltip should adapt the LTR/RTL direction and in result a left tooltip will go right on a RTL layout.
So I think at some point we should rename left and right to start and end, so the name won't be confusing for the opposite direction.
Or to avoid a breaking change we can add start and end as aliases for left and right.

As a result, these new class names should use some name other than start or end. Maybe tooltip-tail-start or something. Let me know if you have any suggestions.

[pdanpdan]

Maybe tooltip-align-start?

[saadeghi]

I think tooltip-tail-start would be more understandable than tooltip-align-start.

It may not be clear what is align especially when the other class names are already changing the alignment from top, bottom, etc.

But tail is more clear. If we want the tail to be at the start, we would use tooltip-tail-start.

[pdanpdan]

Are you changing the names or should I go with the rename?

[saadeghi]

I will rename after merging to v5.6 branch 👍
I'm also adding start and end as aliases for left and right