Add nested file detection for Dependency Scanning

What does this MR do?

This MR is a fix for !30784 (merged)

Note that exists rules support globbing but using fnmatch which doesn't really support regexes. So in order to test matching up to a depth of 2, the {Gemfile.lock,*/Gemfile.lock,*/*/Gemfile.lock} rule was the best matcher I could find. I did not use the **/Gemfile.lock glob because that would change the behaviour of Dependency Scanning on projects that formerly did not have a detection on matching files at depth >2 but all of a sudden start getting detections.

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

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• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team