Disable modal and enable a tooltip when clone button is disabled.
Disable modal and enable a tooltip when clone button is disabled.

Previously, the onClick modal would still fire even if the button was disabled. Also, the tooltip wouldn't reflect why the button is disabled. This change fixes both of those.

jupyterlab/jupyterlab-git,jupyterlab/jupyterlab-git,jupyterlab/jupyterlab-git