revlog: deprecate direct `nodemap` access Now that all in-core user have been updated to the new API, we can deprecated direct access to nodemap. Differential Revision: https://phab.mercurial-scm.org/D7362

#require black

  $ cd $RUNTESTDIR/..
  $ black --config=black.toml --check --diff `hg files 'set:**.py - mercurial/thirdparty/** - "contrib/python-zstandard/**"'`