Revisit names of filter commands

[jrieken]

Testing #141346

The names seem a bit overly specific, like "Code Cell Outputs" could just be "Cell Outputs" (as in the output switcher) or "Outputs". Also "outputs" is plural while others are singular

[rebornix]

Good suggestion, Cell Output is a good candidate.

[rebornix]

I wonder if we should also change Code Cell Source to Code Source to align with Markdown Source but not sure if that would be too ambiguous.