## Summary
Relates to #970.
Add new `bad-format-character` Pylint rule.
I had to make a change in `crates/ruff_python_literal/src/format.rs` to
get a more detailed error in case the format character is not correct. I
chose to do this since most of the format spec parsing functions are
private. It would have required me reimplementing most of the parsing
logic just to know if the format char was correct.
This PR also doesn't reflect current Pylint functionality in two ways.
It supports new format strings correctly, Pylint as of now doesn't. See
pylint-dev/pylint#6085.
In case there are multiple adjacent string literals delimited by
whitespace the index of the wrong format char will relative to the
single string. Pylint will instead reported it relative to the
concatenated string.
Given this:
```
"%s" "%z" % ("hello", "world")
```
Ruff will report this:
```Unsupported format character 'z' (0x7a) at index 1```
Pylint instead:
```Unsupported format character 'z' (0x7a) at index 3```
I believe it's more sensible to report the index relative to the
individual string.
## Test Plan
Added new snapshot and a small test in
`crates/ruff_python_literal/src/format.rs`.
---------
Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>
