Better support for hvPlot .interactive

[jbednar]

The new .interactive functionality in hvPlot is great, making it simple to make little Panel apps with linked plots:

import panel as pn, xarray as xr, holoviews as hv, hvplot.xarray
pn.extension()

ds = xr.tutorial.open_dataset('air_temperature')
image = ds.hvplot('lon', 'lat')
stream = hv.streams.PointerXY(source=image, x=-88+360, y=40)
timeseries = ds.interactive.sel(lon=stream.param.x, lat=stream.param.y,
                                method="nearest").hvplot('time')

pn.Column(image, timeseries.dmap())

However, at first I thought it didn't work, because I had passed in timeseries instead of timeseries.dmap(). Can Panel add a Pane type for hvPlot interactive objects (image here is hvplot.xarray.XArrayInteractive, but there's presumably hvplot.pandas.PandasInteractive, etc.) so that users don't have to think about the type that .interactive....hvplot() returns, and Panel will just display it? Right now Panel happily accepts timeseries but silently ignores it.