Add last-execution info per cell

[nstrayer]

Right now there's no way to tell info about when a cell last ran. E.g. how long it took, what order it was in, if it ran at all, etc...

This info should probably be added in a tooltip to avoid visual clutter.

[ntluong95]

Some ideas:

DataLab - DataCamp

DeepNote

Noted that the current animation when running cell in Notebook 2.0 doesn't show when you are using dark theme