Should we extract vega5 renderer from JupyterLab core?

[fcollonval]

Problem

Recently the vega5 package has seen a contribution to update for vega-lite v5. This highlight two things:

• Updating it for user requires a JupyterLab release although this is a mime renderer and should be easily support lots of JupyterLab version
• The core version of a renderer may not be the best version for users (although I think vega is not so problematic in that regard)

Proposed Solution

Move vega mime renderer to jupyter renderers repository.