BUGFIX: line_kws.color is of no effect in distribution plot

[youqingxiaozhua]

In the distribution plot (such as seaborn.histplot), both color and line_kws['color'] parameters are allowed to be passed to control the colors of bars and lines, respectively. However, current codes directly take the line color from the bar color while ignoring the line_kws['color']. This pull request fixes this by looking at line_kws['color'] first, and adopting bar color only if the line color is not manually set.

[mwaskom]

Can you provide a reproducible example of the issue? I am not sure this is a bug.

[youqingxiaozhua]

Can you provide a reproducible example of the issue? I am not sure this is a bug.

Please see this notebook: https://colab.research.google.com/drive/1Ltc4lJzZjJXGyxdtlSOwtRGry2oMDWT6?usp=sharing