Add the Nadaraya-Watson Channels indicator

[tdgrossi]

Is your feature request related to a problem? Please describe.
The Nadaraya-Watson indicator is in essence the calculation of the Nadaraya-Watson regression, by iterating over the input data, computing the distances between data points, and applying the specified kernel to compute the weights. The predicted response variable is then computed based on these weights. Finally, the predicted response variable is returned as a DataFrame with the column name 'kernel'.

It raised some eye-browns when it was published by LuxAlgo in tradingview, with many youtube videos showing impressive results, albeit with some caveats, such as repainting.

Describe the solution you'd like
An indicator to be created, with upper and lower channels

Inspirational source
https://www.tradingview.com/script/Iko0E2kL-Nadaraya-Watson-Envelope-LuxAlgo/