feat: check if by column is sorted, rather than just checking sorted flag, in group_by_dynamic, upsample, and rolling

[MarcoGorelli]

#16333 Introduced using Series.is_sorted instead of just checking Series.is_sorted_flag

I'd like to suggest doing the same for group_by_dynamic, rolling and upsample. I think this'll make a noticeable ergonomic difference to users

What's missing is, in the case when it's not sorted, to sort on behalf of the user. That's a bit harder to address, but I think already using Series.is_sorted instead of only checking the sorted flag would already be a positive change for users

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Also, I think the current check isn't even correct, as it only checks if the sorted flag doesn't match IsNot, as opposed to checking that it matches Ascending

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.52%. Comparing base (d856b49) to head (af80d86).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16494      +/-   ##
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- Coverage   81.53%   81.52%   -0.01%     
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  Files        1410     1410              
  Lines      185061   185041      -20     
  Branches     2982     2984       +2     
==========================================
- Hits       150885   150853      -32     
- Misses      33660    33672      +12     
  Partials      516      516              

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