Rename the docprovider destination name to avoid conficts

[brichet]

Fix the docprovider extension destination path, following https://github.com/jupyterlab/jupyter-collaboration/pull/280

Fixes https://github.com/jupyterlab/jupyter-collaboration/issues/283

We should probably add some tests (I don't even know how it passed)

[github-actions[bot]]

:point_left: Launch a Binder on branch _brichet/jupyter_collaboration/rename_docproviderextension

[brichet]

The Check Release test seems to be broken on main too.

[davidbrochart]

Thanks a lot Nicolas!