Preset combination plots

I think it'd be nice to have commonly used plots like:

`ds.hvplot.preset.line_area()` (like the line * area in https://hvplot.holoviz.org/user_guide/Plotting.html)
line (show individual data points with alpha set to like 0.05) * line (mean of lines) * area (min + max points)

`ds.hvplot.preset.line_label()`
line * label (label y for the last value of x)

`ds.hvplot.preset.bar_line()` (like http://arctic.som.ou.edu/tburg/products/covid19/files_states/rolling_total_summary.png)
bar (show individual data points) * line (rolling mean)

`ds.hvplot.preset.scatter_violin()` (like https://davidbaranger.com/2018/03/05/showing-your-data-scatter-box-violin-plots/)
scatter (show individual data points) * violin (aggregate of data points)

`ds.hvplot.preset.scatter_hex()`
scatter (show individual data points) * hex (aggregate of data points)

And more