metadata: move computation related to files touched in a dedicated module
This was suggested by Yuya Nishihara a while back. Since I am about to add more
metadata related computation, lets create a new repositories.
Differential Revision: https://phab.mercurial-scm.org/D8587
# Files that just need to be migrated to the formatter.
# Do not add new files here!
mercurial/cext/manifest.c
mercurial/cext/osutil.c
# Vendored code that we should never format:
syntax: glob
contrib/python-zstandard/**.c
contrib/python-zstandard/**.h
hgext/fsmonitor/pywatchman/**.c
mercurial/thirdparty/**.c
mercurial/thirdparty/**.h