Feature request - Allow for generating output without re-running a full notebook

[emcrisan]

Allow for not re-running a full notebook to generate an output (the equivalent of running “save as”). This would make it easier to publish notebooks with computational intensive steps, and would also allow publishing of notebooks which run kernel which isn’t the kernel hosting jupyter (i.e., a kernel selected with “change kernel”). Currently, using “change kernel” results in a “kernel not found” error in nbconvert.

Raised in internal ticket 51892.