[ofs][xs]: do not import local and remote subpackages in top level __init__.py to avoid breakage due to uninstalled dependencies.
[ofs][xs]: do not import local and remote subpackages in top level __init__.py to avoid breakage due to uninstalled dependencies.

  * Importing local means import breaks on systems where you do not have relevant dependencies for specific implementations (e.g. pairtree)

okfn/ofs