Editor support to catch typos in role keywords like USERS: vs. USER:

[willbakst]

Is your feature request related to a problem? Please describe.
When writing prompt templates, there's potential for annoying, silent bugs when there's a typo in a role keyword (i.e. writing USERS: won't get parsed properly and there's no indication that this is happening.

Of course, users can always opt-out of the prompt template and write the messages themselves, but it would be better to instead provide better support for prompt templates to avoid these bugs without having to opt-out.

Describe the solution you'd like
Something like a VSCode or mypy or ruff extension that can check for common typos/mispellings and notify the user in their editor to help avoid these bugs.

Describe alternatives you've considered
Previously errors would be thrown for incorrect keywords, but this prevented full user control, which is against mirascope's principles.