trusting all extensions

Hello,

I'm writing widgets for notebooks, and I wanted to know if there is a way to trust all extensions by default?

I don't have to have to re-trust the widget every time I remove and replace it during development:

`jupyter nbextension enable --py --sys-prefix widgetsnbextension`

Thank you,

Andrew

Start with the `jupyter nbextension enable --py --sys-prefix widgetsnbextension` command and investigate how extension trust is currently handled for notebook widgets. Define the intended default-trust behavior and its security boundaries before identifying the implementation and validation needed to avoid repeated re-trust during development.

Written by the indexing model from the issue text.