Add Scale.label interface for formatting ticks

[mwaskom]

e.g.

(
    so.Plot(tips, "total_bill")
    .add(so.Bar(), so.Hist())
    .scale(x=so.Continuous().label(like="${x:.0f}"))
)

(
    so.Plot(planets, "distance")
    .add(so.Bar(), so.Hist())
    .scale(x=so.Continuous().label(unit="pc"))
)

This also makes log transformed scales default to a log formatter (closes #2840)

(
    so.Plot(planets, "distance")
    .add(so.Bar(), so.Hist())
    .scale(x="log")
)

This also shortens the transform Scale parameter to trans, as testing revealed that typing out transform is a little cumbersome.

[codecov]

Codecov Report

Merging #2877 (d62a218) into master (ecba2dc) will increase coverage by 0.02%.
The diff coverage is 97.22%.

@@            Coverage Diff             @@
##           master    #2877      +/-   ##
==========================================
+ Coverage   98.13%   98.15%   +0.02%     
==========================================
  Files          69       69              
  Lines       22271    22400     +129     
==========================================
+ Hits        21855    21987     +132     
+ Misses        416      413       -3     

Impacted Files	Coverage Δ
tests/test_categorical.py	99.77% <ø> (ø)
seaborn/_core/plot.py	94.60% <94.44%> (ø)
seaborn/_core/scales.py	89.52% <94.92%> (+2.70%)	⬆️
seaborn/_core/properties.py	99.15% <100.00%> (ø)
seaborn/_marks/base.py	98.26% <100.00%> (+0.68%)	⬆️
seaborn/_stats/histograms.py	98.82% <100.00%> (ø)
tests/_core/test_plot.py	98.39% <100.00%> (ø)
tests/_core/test_scales.py	100.00% <100.00%> (ø)

[mwaskom]

Docs still need some tweaking but merging to do that on the pydata-theme branch.