fix #691 - support root in pyproject.toml even for cli

[RonnyPfannschmidt]

superseeds #702 which served as inspiration
adds integration tests

[baodrate]

@RonnyPfannschmidt A minor edge case, but it seems that this PR still behaves oddly when both -c and -r are specified. When -c is specified, -r seems to be resolved relative to the config file specified by -c. e.g. given a directory tree:

repo
├── .git
└── subdir
    └── pkg
        └── pyproject.toml

specifying -r relative to a PWD doesn't work:

repo/subdir$ python3 -m setuptools_scm -c pkg/pyproject.toml -r ..
('ERROR: no version found for', Namespace(root='..', config='pkg/pyproject.toml', strip_dev=False, command=None))    

you have to specify it as a path relative to the config file instead:

repo/subdir$ python3 -m setuptools_scm -c pkg/pyproject.toml -r ../..
../setuptools_scm/config.py:256: UserWarning: root .. is overridden by the cli arg ../..
  warnings.warn(
1.0.4.dev0+g7d7bd26.d20220627

My intuition as a CLI user is that relative paths specified on the command line are relative to the PWD.

If this is intended behavior, it should at least be mentioned in the --help or documentation. (although root .. is overridden by the cli arg seems to imply that -r should retain its behavior whether or not -c is specified)

I addressed this case in my PR against #702 (you may have missed me mentioning it)

[RonnyPfannschmidt]

Tja for the note

Root is intentionally relative to the config file

But we ca take a look at managing the cli one relative to the cwd