BUG: Assorted DTA/TDA/PI bugfixes

[jbrockmendel]

Fixes a problem with tz-aware DatetimeArray.round (ref #24038)
Fixes PI, PA, DTA failing to validate lengths when doing comparisons against length-1 instances (ref #23078)
Pins names to a handful of methods that currently don't have them (working on a separate branch that checks these systematically; these are the low-hanging fruit)

• closes comparison between two PeriodIndexes doesn't validate length #23078
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

[codecov]

Codecov Report

Merging #24397 into master will decrease coverage by 49.31%.
The diff coverage is 58.33%.

@@             Coverage Diff             @@
##           master   #24397       +/-   ##
===========================================
- Coverage    92.3%   42.99%   -49.32%     
===========================================
  Files         162      162               
  Lines       51875    51886       +11     
===========================================
- Hits        47883    22308    -25575     
- Misses       3992    29578    +25586

Flag	Coverage Δ
#multiple	?
#single	42.99% <58.33%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
pandas/core/arrays/datetimelike.py	48.58% <0%> (-47.94%)	⬇️
pandas/core/arrays/period.py	37.95% <0%> (-60.55%)	⬇️
pandas/core/series.py	49.38% <100%> (-44.34%)	⬇️
pandas/core/ops.py	55.64% <100%> (-38.63%)	⬇️
pandas/core/indexes/base.py	56.17% <100%> (-40.1%)	⬇️
pandas/core/arrays/timedeltas.py	40.13% <50%> (-47.03%)	⬇️
pandas/core/arrays/datetimes.py	66.37% <50%> (-31.87%)	⬇️
pandas/io/formats/latex.py	0% <0%> (-100%)	⬇️
pandas/core/categorical.py	0% <0%> (-100%)	⬇️
pandas/io/sas/sas_constants.py	0% <0%> (-100%)	⬇️
... and 127 more

---

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[codecov]

Codecov Report

Merging #24397 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #24397      +/-   ##
==========================================
- Coverage    92.3%    92.3%   -0.01%     
==========================================
  Files         163      163              
  Lines       51946    51958      +12     
==========================================
+ Hits        47949    47959      +10     
- Misses       3997     3999       +2

Flag	Coverage Δ
#multiple	90.71% <100%> (-0.01%)	⬇️
#single	43% <64.28%> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/core/arrays/datetimelike.py	96.14% <100%> (-0.22%)	⬇️
pandas/core/series.py	93.72% <100%> (ø)	⬆️
pandas/core/arrays/period.py	98.48% <100%> (ø)	⬆️
pandas/core/arrays/timedeltas.py	86.91% <100%> (+0.05%)	⬆️
pandas/core/ops.py	94.28% <100%> (+0.02%)	⬆️
pandas/core/arrays/datetimes.py	97.6% <100%> (-0.18%)	⬇️
pandas/core/indexes/base.py	96.27% <100%> (ø)	⬆️

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[jreback]

minor code comments. can you add whatsnews as needed.

[jreback]

is this orthogonal to #23078, should close that one?

[jbrockmendel]

is this orthogonal to #23078, should close that one?

This closes #23078, should be reflected in the OP.

[jbrockmendel]

i think comments have been addressed

[jreback]

thanks. pls followup on the ops name tests at some point.