dirstatemap: remove `_insert_entry` This was needed as a compatibility layer for the Python and Rust implementations, but it is not called from anywhere in Rust anymore. The two remaining calls have been inlined. Differential Revision: https://phab.mercurial-scm.org/D12501

# name space package to host third party extensions
import pkgutil

__path__ = pkgutil.extend_path(__path__, __name__)