Fix language stats for the repo

[sgammon]

Related to #1073

Update .gitattributes to improve language stats detection for Java, JavaScript, and Rust files.

• JavaScript Files:
  • Remove the -linguist-detectable attribute from *.js and *.mjs files.
• Java Files:
  • Update **/package-info.java to be linguist-detectable.
• Rust Files:
  • Add the linguist-detectable attribute to *.rs files.

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