Auto3DSeg BundleGen clobbers existing bundles

[pwrightkcl]

Problem
I just discovered the hard way that BundleGen completely clobbers existing bundles, not only overwriting files, but deleting files it does not write (like training output).

Desired solution
It would be nice to have a clobber=True kind of option, where the default would be to give a warning that the bundle directory already exists.

Example code
Here are the relevant parts of what I ran:

from monai.apps.auto3dseg import BundleGen


bundle_generator = BundleGen(
    algo_path=work_dir,
    data_stats_filename=datastats_file,
    data_src_cfg_name=input_yaml,
)

bundle_generator.generate(work_dir, num_fold=5)