Decouple interactive Beam from Jupyter

Some aspects of interactive Beam (e.g. triggering execution with ib.collect) make sense to use outside of a Jupyter notebook. We should make sure that use-cases like this are possible, and we only require a notebook if it's actually necessary. In my mind that should just be features that are _explicitly_ integrating with Jupyter, like side panels, custom magics, etc...

Things like caching and plotting tools even make sense to use outside of Jupyter (a plotting tool can return a handle that the user could use to save the plot as an image).

Imported from Jira [BEAM-14515](https://issues.apache.org/jira/browse/BEAM-14515). Original Jira may contain additional context.
Reported by: bhulette.