## Summary
When running ruff in verbose mode with `-v`, the first debug logs show
where the config settings are taken from. For example:
```
❯ ruff check ./some_file.py -v
[2023-11-17][00:16:25][ruff_cli::resolve][DEBUG] Using pyproject.toml (parent) at /Users/vince/demo/ruff.toml
```
This threw me off for a second because I knew I had no python project
there, and therefore no `pyproject.toml` file. Then I realised it was
actually reading a `ruff.toml` file (obvious when you read the whole
print I suppose) and that the pyproject.toml is a hardcoded string in
the debug log.
I think it would be nice to tweak the wording slightly so it is clear
that the settings don't neccessarily have to come from a
`pyproject.toml` file.
**Summary** This includes two changes:
* Allow setting `-v` in `ruff_dev`, using the `ruff_cli` implementation
* `debug!` which ruff configuration strategy was used
This is a byproduct of debugging #6187.
**Test Plan** n/a
## Summary
We want to ensure that once formatted content stays the same when
formatted again, which is known as formatter stability or formatter
idempotency, and that the formatter prints syntactically valid code. As
our test cases cover only a limited amount of code, this allows checking
entire repositories.
This adds a new subcommand to `ruff_dev` which can be invoked as `cargo
run --bin ruff_dev -- check-formatter-stability <repo>`. While initially
only intended to check stability, it has also found cases where the
formatter printed invalid syntax or panicked.
## Test Plan
Running this on cpython is already identifying bugs
(https://github.com/astral-sh/ruff/pull/5089)
