Allow x=/y= to control paired scales and limits

[mwaskom]

This PR enhances the behavior of Plot.scale and Plot.limit when using Plot.pair such that all paired axes can be configured in one step by passing setting just x or y. Currently, each x0, x1, ... must be defined. The common scale/limit is treated as a fallback, so specific variables can still be defined separately:

(
    so.Plot(planets, x="year")
    .pair(y=["orbital_period", "mass", "distance"])
    .scale(y="log", y1="sqrt")
    .add(so.Dots())
)

Closes #2910

[codecov]

Codecov Report

Merging #3458 (3f81b67) into master (082486d) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3458   +/-   ##
=======================================
  Coverage   98.33%   98.33%           
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  Files          75       75           
  Lines       24438    24449   +11     
=======================================
+ Hits        24030    24041   +11     
  Misses        408      408           

Files Changed	Coverage Δ
seaborn/_core/plot.py	98.30% <100.00%> (+<0.01%)	⬆️
tests/_core/test_plot.py	98.82% <100.00%> (+<0.01%)	⬆️