HLS data download tmp path

[dshean]

Final cell of https://github.com/uw-cryo/DeepDEM/blob/main/notebooks/0b_Download_HLS_data.ipynb

shutil.rmtree(Path("../data/common_files/tmp"))
This should be previously defined download_tmp_path

I'm not sure about the glob and merge here, and current approaches involving centralized common_files outside of the site data directory. Will create issues for multiple sites.

This is lower priority for now, but should be addressed.