Add badges for achievements

[ArthurSonzogni]

There are a few Google internal badges about Chromium. It would be interesting to have something open to all, and targetted to the web engines developers.

Possible ideas:

• [ ] Milestone Marathon Longest consecutive streak of contributing to Chrome milestones. This could have different tiers (bronze, silver, gold) for different streak lengths.
• [ ] Fuzzing: I created a fuzzer.
• [ ] Polyglot: Awarded for contributed to multiple repositories: V8, Dawn, etc...
• [ ] h-index: Contributed at least 10n patch to n repositories.
• [ ] Special milestone: Awarded for having contributed before some specific version: M10, M50, M100
• [ ] Commit count! Awarded for reaching specific commit count milestones in Chromium (100, 500, 1000, etc.).
• [ ] Contribution type: I did more code reviews than authored CL.
• [ ] Large delete: I deleted more than 10000 lines of code in a single patch.
• [ ] Zero carbon emission: I deleted more code than I added.
• [ ] Legacy builder: For long-time contributors with a significant history in the Chromium project.

[ArthurSonzogni]

Important ideas:

• Keep badges difficult to get to keep them valuable: < 10% developers get one instance.
• Attach data to badge, so that developers can see some "intermediate" score in between two versions of badges.
• Make badges diverse or funny, so that most get several instances.