add ESRI wayback as an available basemap in SEPAL

[12rambau]

When selecting extra layers in a recipe the only available very high-resolution dataset is the Google imagery one.
Would it be possible to add ESRI wayback? https://livingatlas.arcgis.com/wayback/#active=47963&mapCenter=-115.299%2C36.064%2C14

I'm trying to perform visual interpretation and let's face it it's impossible even using NICFI data:

I have done it in Python in a script, I would be happy to help design something (the complex part is to get the ids and dates from the ESRI metadata, the numbers make no sense.