Fix add_all_untracked to return code as expected
Fix add_all_untracked to return code as expected

GitAddAllUnstagedHandler in handlers.py expects the dictionary returned by this function to have "code" as a key. Seems like this function is the only one that had it's return statement not modified by: https://github.com/jupyterlab/jupyterlab-git/commit/80aee60bce2c195bd65ed60551b818a209a04e5f#diff-041cb4cfb7143f3bbcdd07d28dffa92c

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