revlog: code for `revlogv0` in its own module This code is mostly unused compatiblity code. Yet it take a prohiminent place in the `revlog.py` module. That module is already quite big, so we move all that code in a dedicated module. Differential Revision: https://phab.mercurial-scm.org/D10511

[build-system]
requires = ["setuptools", "wheel"]
build-backend = "setuptools.build_meta"

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