[ENH] n_features and feature_names metadata field for table mtypes

[fkiraly]

This PR adds n_features and feature_names metadat field for data table mtypes - similar to the attributes of the same name in sklearn.

This will be useful for cleaner input/output queriability in a variety of places, and further sklearn compatibility.

Similar to sktime/sktime#5596 (for time series)

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (ffbde52) 64.09% compared to head (5948f3d) 64.27%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
skpro/datatypes/_table/_check.py	91.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #150      +/-   ##
==========================================
+ Coverage   64.09%   64.27%   +0.18%     
==========================================
  Files         104      104              
  Lines        5534     5568      +34     
  Branches     1022     1040      +18     
==========================================
+ Hits         3547     3579      +32     
- Misses       1705     1706       +1     
- Partials      282      283       +1     

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