parser: warn on unused imported functions used via import math { sin, cos }

[Delta456]

Fixes #17432

🤖 Generated by Copilot at 1d993db

This pull request fixes some issues with the checker's detection of unused imports in the parser. It adds or removes import registrations for modules that contain functions or types that are used or unused in the file. It also adds a test case for the unused import warning.

🤖 Generated by Copilot at 1d993db

• Register imported modules that contain used functions or types to avoid checker warnings (link, link)
• Remove unnecessary registration of imported module that is aliased (link)
• Add test case for checker warning on importing unused symbols from a module (link, link)

[Delta456]

Special thanks to @spytheman for helping to solve the issue effectively!