Feature: Notebook Editor, Interactive Window, Python Editor cells

Add ability to set metadata tags on a cell, like notebook classic supports in the gif below (but maybe with a better interface for it).

Description

Cell tags are used as a convention based pattern for converting notebooks in a few contexts. The papermill library uses the parameters and injected-parameters tags to manage user inputs to notebook executions. NBConvert has notebook manipulation processors that filter or convert cells based on tags. Overall while it was originally used for metadata matching purposes, it's use for production execution paths has become a necessity with Jupyter today. Have a minimal way to manage the cell tags would go a long way for cross-tooling support.