ENH: Allow ignoring python_min hints

[h-vetinari]

Some feedstocks need to opt-out of the test pins for python_min, for example due to being used elsewhere as a downstreams: test against other python versions (c.f. conda-forge/conda-forge.github.io#2387, conda-forge/conda-smithy-feedstock#331, conda-forge/setuptools-feedstock#371).

Given this reality, we shouldn't force those feedstocks to live with linter warnings in perpetuity, but give them a way to silence the linter. In #2090, the following mechanism was introduced

linter:
  skip:
    - lint_noarch_selectors

This could easily be extended to allow

linter:
  skip:
    - hint_python_min

[isuruf]

Or if we want to be more explicit

linter:
  skip:
    - hint_python_min_in_host
    - hint_python_min_in_run
    - hint_python_min_in_test_requires

[rgommers]

Another lint I ran into that needed skipping was the check about a build backend being present for a noarch recipe (don't have the exact message at hand now). The reason is that meson-python has an in-tree build backend (namely, itself), so that it doesn't need an external one. This is probably going to be true for all build backends and perhaps a handful of other projects.

This could be handled via a linter skip, or by the linter also looking at the [build-requires] section of pyproject.toml and disabling the warning if backend-path is present.

I like the proposed syntax in the comments above.

[xylar]

@rgommers, it might be best to make a separate issue for that because it's not related to python_min. But I agree. poetry-core is another package where the backend is provided in code and the warning could be skipped.