Fix gitattributes parser to apply patterns to subdirectories

What does this MR do and why?

Contributes to #513617 (closed)

Problem

Patterns like Dockerfile.* are currently applied only to the root directory of the repository.

• Dockerfile.local - match
• docker/Dockerfile.local - no match

However, it's incorrect. Git captures both file paths as matches. So GitLab should follow the same logic.

Solution

Use File::FNM_PATHNAME to support glob pattern matching.

References

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• gitattributes not applying in subdirectories (#513617 - closed)

MR acceptance checklist

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Before	After (FROM is highlighted)

How to set up and validate locally

1. Enable feature flag Feature.enable(:attribute_parser_fix)
2. Clone an example project (or recreate it locally): https://gitlab.com/iamthad/gitattributes-bug-repro
3. Visit https://<path_to_project_in_gdk>/-/blob/main/docker/Dockerfile.local?ref_type=heads
4. The code should be highlighted