Add jupyter(lab)-lsp to stack

[bollwyvl]

Elevator Pitch

Add jupyter-lsp python and js packages to the stack of built packages.

Motivation

Evaluating LSP in JupyterLite will likely require some upstream changes.

Design Ideas

Aside from a few interrelated steps, such as generating js types from schema, this should be relatively straightforward.

[bollwyvl]

Looks like the patches that mention jupyter-lsp/jupyterlab-lsp#959 would need to be resolved before this could continue in anger. In the near term, jupyter_lsp is worth bringing in to avoid pulling much of the stack during the environment solve.