Make DTA/TDA/PA return NotImplemented on comparisons

[jbrockmendel]

Before implementing a boilerplate decorator like in #24282, going through to standardize the affected behaviors.

[codecov]

Codecov Report

Merging #24643 into master will decrease coverage by <.01%.
The diff coverage is 90%.

@@            Coverage Diff             @@
##           master   #24643      +/-   ##
==========================================
- Coverage   92.37%   92.37%   -0.01%     
==========================================
  Files         166      166              
  Lines       52379    52382       +3     
==========================================
+ Hits        48386    48387       +1     
- Misses       3993     3995       +2

Flag	Coverage Δ
#multiple	90.79% <90%> (-0.01%)	⬇️
#single	43.02% <50%> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/core/arrays/period.py	98.52% <100%> (-0.02%)	⬇️
pandas/core/arrays/datetimes.py	97.69% <100%> (-0.16%)	⬇️
pandas/core/indexes/datetimelike.py	98.52% <100%> (ø)	⬆️
pandas/core/arrays/timedeltas.py	88.03% <50%> (-0.15%)	⬇️

---

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[codecov]

Codecov Report

Merging #24643 into master will decrease coverage by <.01%.
The diff coverage is 92.3%.

@@            Coverage Diff             @@
##           master   #24643      +/-   ##
==========================================
- Coverage   92.37%   92.37%   -0.01%     
==========================================
  Files         166      166              
  Lines       52379    52383       +4     
==========================================
+ Hits        48386    48388       +2     
- Misses       3993     3995       +2

Flag	Coverage Δ
#multiple	90.79% <92.3%> (-0.01%)	⬇️
#single	43.02% <61.53%> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/core/arrays/period.py	98.52% <100%> (-0.02%)	⬇️
pandas/core/arrays/datetimes.py	97.69% <100%> (-0.16%)	⬇️
pandas/core/indexes/datetimelike.py	98.52% <100%> (+0.01%)	⬆️
pandas/core/arrays/timedeltas.py	88.03% <50%> (-0.15%)	⬇️

---

Continue to review full report at Codecov.

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d106e99...b69c2cb. Read the comment docs.

[jreback]

lgtm ping on green.

[jbrockmendel]

ping

[jreback]

thanks!