unused_ignore_directives doesn't work on stdlib/3rd party imports

[DetachHead]

# tach.toml
[rules]
unused_ignore_directives = "error"

# tach-ignore
from typing import Iterable

> tach check
✅ All modules validated!

[DetachHead]

i guess fixing this would need to account for tach-ignore comments that are intended for tach check-external rather than tach check

[DetachHead]

maybe tach check-external can instead be part of tach check which can be enabled or disabled using a rule, (like with unused_ignore_directives):

# tach.toml
[rules]
check_external = true

i imagine doing this would also address gauge-sh/tach-vscode#17

[emdoyle]

For now, it is simpler to hide tach-ignore comments which refer to imports that are irrelevant. This won't flag the comment in your example during tach check, but it will flag it during tach check-external.

This should be easy to reason about for now, but we want to hold off on using global config to enable the external use case like this. For the VSCE issue, I think an LSP setting to enable the external check makes sense though. After some more work to give consistent structure to external dependency errors, I can work on that.