[K9VULN-2230] Add test file detection for Java

[jasonforal]

What problem are you trying to solve?

The analyzer doesn't accurately classify Java files that contain or are related to tests.

What is your solution?

• Implement a parser for Java package imports. (Language reference here)
• Add detections for common Java test packages (here).

Alternatives considered

What the reviewer should know

[jasonforal]

Rebasing on main to solve merge conflict here and here (this PR was implemented before the Python implementation was merged, so we need to reconcile the match arms that newly contain Python)