Warn when an `include`, `lint.per-file-ignores` (maybe `exclude`) pattern does not match any files

After refactoring, especially if folders are renamed, we might sometimes forget to update the folder name in `ruff.toml` / `.ruff.toml` / `pyproject.toml`:

```toml
target-version = "py311"

line-length = 90

output-prefer-rule-codes = true

include = [
"py-src/**/*.{py,pyi}", # If the folder name has changed, for example, to "pysrc", ruff will simply say nothing
]
```

I'm not sure about the `exclude` patterns, since they might be generated somewhere in CI, and the user might not have those files locally, so I don't think we should do that for `exclude`

Start by tracing how ruff.toml, .ruff.toml, and pyproject.toml settings are loaded and how include and lint.per-file-ignores patterns are matched. Check the existing behavior for patterns matching no files, while treating exclude as an explicit scope question. Done means the applicable unmatched patterns produce a clear warning without incorrectly warning for excluded or unavailable files.

Written by the indexing model from the issue text.