[ENH] deep_equals - clearer return on diffs from dtypes and index, relaxation of MultiIndex equality check

[fkiraly]

This PR improves error messaging in deep_equals and makes checks on pandas based indices stricter.

Changes:

• dtypes of pd.DataFrame-s are now checked explicitly
• providing a clearer return on pd.DataFrame dtypes no being equal
• pd.Index dtypes are now checked explicitly
• index equality check is slightly relaxed. DataFrame.equals may consider MultiIndex as unequal due to irrelevant typing in some python versions, so instead we now explicitly check equality in names, values

Mirror of sktime/sktime#5560, for links to sktime dask failures see there.

[codecov]

Codecov Report

Attention: 21 lines in your changes are missing coverage. Please review.

Comparison is base (12a1884) 84.19% compared to head (11f955b) 83.94%.
Report is 6 commits behind head on main.

Files	Patch %	Lines
skbase/utils/deep_equals/_deep_equals.py	32.25%	21 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #246      +/-   ##
==========================================
- Coverage   84.19%   83.94%   -0.25%     
==========================================
  Files          43       43              
  Lines        2891     2922      +31     
==========================================
+ Hits         2434     2453      +19     
- Misses        457      469      +12     

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