config: add `--shared` flag to edit config file of shared source
With `format.exp-share-safe` enabled, we now read the `.hg/hgrc` of the shared
source also.
This patch adds `--shared` flag to `hg config` command which can be used to edit
that shared source config file. It only works if the repository is shared one
and is shared using the safe method.
Differential Revision: https://phab.mercurial-scm.org/D8659
[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true