Add support for excluding functions from coverage with attribute

[benjaminfuchs]

PR Summary

Fixes #2268

This pull request introduces support for excluding functions from code coverage analysis using the [ExcludeFromCodeCoverageAttribute()] attribute.

Changes:

• Updated the Get-CommandsInFile function to skip AST nodes within functions marked with [ExcludeFromCodeCoverageAttribute()].
• Added IsExcludedByAttribute to check if a function has the exclusion attribute applied, either fully qualified or resolved through using namespace.
• Implemented Get-NamespacesFromScript to identify and apply using namespace declarations for resolving unqualified attribute names (not sure if similar logic already exists in the codebase).
• Updated tests to verify exclusion functionality.

PR Checklist

• PR has meaningful title
• Summary describes changes
• PR is ready to be merged
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• Tests are added/update (if required)
• Documentation is updated/added (if required)

[benjaminfuchs]

If the approach is valid, I'll refine the tests and add proper documentation. Feedback is welcome!