allow to opt-out from css pure linting

[jantimon]

This PR adds support for the /* cssmodules-pure-no-check */ comment which allows users to disable the pure CSS modules check for the entire file (similar to // @ts-nocheck)

The feature is a port from postcss

Details

• Parsing Change: Detects the /* cssmodules-pure-no-check */ comment at the beginning of the CSS file and sets pure to false in css_modules options.
• Test Cases: Added tests to verify the functionality, ensuring the comment works as expected even with preceding comments.

Solves #889