[SPARK-58971][PS] Add pct, na_option, and axis parameters to Series.rank and DataFrame.rank

[jzhan-2026]

What changes were proposed in this pull request?

Add na_option, pct, and axis parameters to Series.rank(), and na_option and pct to
DataFrame.rank(), to match the pandas API.

• na_option ('keep'/'top'/'bottom'): controls how NaN values are ranked
• pct: expresses ranks as percentile fractions in (0, 1]
• axis on Series.rank(): accepts 0/'index' only, added for API compatibility

Why are the changes needed?

The pandas-on-Spark implementations were missing these parameters, making it harder to migrate
pandas code to Spark without modification. DataFrame.rank was tracked in SPARK-46167; this PR
also covers Series.rank.

Does this PR introduce any user-facing change?

Yes. Two new keyword parameters on Series.rank() and DataFrame.rank(). Defaults are
unchanged so existing code is unaffected.

>>> ps.Series([1, float('nan'), 2]).rank(na_option='top')
0    2.0
1    1.0
2    3.0


>>> ps.Series([1, 2, 2, 3]).rank(pct=True)
0    0.25
1    0.625
2    0.625
3    1.0

How was this patch tested?

New test method test_rank_pct_na_option in test_compute.py and new cases in test_stat.py
covering all methods, both axes, combined parameters, and invalid input errors.

Was this patch authored or co-authored using generative AI tooling?

This patch was co-authored with AI assistance (Claude Sonnet 4.6).