Handle non-string dynamic imports gracefully

[renanccastro]

Summary

• When a dynamic import uses a variable instead of a string literal (e.g. await import(varName)), the parser now logs a warning and skips the import instead of crashing the entire lint run.
• This was encountered in a large Meteor project where Sentry was dynamically imported based on a runtime condition.

Test plan

• Verified on a large Meteor 2 codebase (~3000+ files) that the plugin no longer crashes
• Warning is logged so users are aware the import was skipped