Support labels by

[ahuang11]

Closes #1094

import hvplot.pandas
import pandas as pd

df = pd.DataFrame(
    {'City': ['Buenos Aires', 'Brasilia', 'Santiago'],
     'Country': ['Argentina', 'Brazil', 'Chile'],
     'Latitude': [-34.58, -15.78, -33.45],
     'Longitude': [-58.66, -47.91, -70.66]})
df.hvplot.labels("Longitude", "Latitude", "City", by="City")

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.40%. Comparing base (e5e71d6) to head (85ccf13).
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1347      +/-   ##
==========================================
+ Coverage   87.36%   87.40%   +0.04%     
==========================================
  Files          50       50              
  Lines        7471     7497      +26     
==========================================
+ Hits         6527     6553      +26     
  Misses        944      944              

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[maximlt]

I just added a simple test to exert subplots=True with by.

[maximlt]

Unrelated test failures.