Formatter: Improve handling of syntax errors

[zanieb]

The current user-facing messaging for syntax errors encountered during formatting are not friendly and are significantly worse than the linter's. The error should be normalized into a message instead of using the debug representation of ParseError

e.g.

Line number not included (existing issue):

error: Failed to format commands/liberrors.py: source contains syntax errors: ParseError { error: UnrecognizedToken(Name { name: "THE_INVALID_FILE" }, None), offset: 208, source_path: "<filename>" } 157 files left unchanged

Cell number not included in notebook errors

error: Failed to format course/videos/domain_adaptation.ipynb: source contains syntax errors: ParseError { error: UnrecognizedToken(Rpar, None), offset: 70, source_path: "<filename>" }

The previous error is much nicer via the linter

error: Failed to parse course/videos/domain_adaptation.ipynb:cell 9:1:71: Unexpected token ')'

[charliermarsh]

I can fix these.

[zanieb]

It'd also be nice to exit with a specific code if we only fail due to syntax errors rather than some sort of other failure :) that way we can report it nicely in the ecosystem checks instead of treating it as a failed run of Ruff.