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

[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true