Removal of sendToCloud button

[nicolaskruchten]

We need to document how to turn it back on via config

[nicolaskruchten]

New in 1.43.0 plotly/plotly.js#3307

[cldougl]

in addition to turning it back on in each plotly.js example (#1197) update the config doc: https://plot.ly/javascript/configuration-options/