Implement a new contribution model #186415

The Flutter project has fostered a large and vibrant community of contributors. However, our current community management model, which has evolved organically, is reaching its scalability limits. The following proposal outlines a plan to introduce a formal, data-driven contributor ladder that will empower our community, create a scalable membership structure, and ensure the long-term health of the project by recognizing and celebrating contributors to help build Flutter's future.

See the new model and give feedback on ➡️ Flutter Contributor Ladder ⬅️

We will incorporate feedback through this Maintainer's Month (May), and begin implementation in June through a new flutter/contributors repository.

This will entail (to update as we process feedback):

• flutter/contributors repo set-up
  • templates, legacy AUTHORS files, analysis scripts, membership lists, process docs
• Update existing docs, contributing guide, contributor access
  • flutter/flutter
  • flutter/website
  • flutter/packages
  • etc.
• Set up Github teams with permissions
  • Maintainers (write), Partners
  • Committers (write)
  • Reviewers (triage)
  • flutter-hackers (remove permissions, make parent of all)
  • Dasher Emeritus
• Update flutter/cocoon for new approval flow
• Set up Google Group
  • Set up form for private channel on Discord for intake of existing hackers.
• Update Discord
  • Introduce new channels
• Update moderation roles