Rename `tools.github.repos` to `tools.github.allowed-repos`

[dsyme]

@lpcox @pelikhan In this declaration, I think users will be confused by repos: .

It means "Restrict the repositories the tools can access" but I suspect people will think it means "allow my tools to access these repositories".

I wonder if allowed-repos: or something may be better

  github:
    mode: remote
    toolsets: [default]
    allowed-repos:
      - "myorg/*"
      - "partner/shared-repo"
      - "myorg/api-*"
    min-integrity: approved

[pelikhan]

add a codemod to rewrite repos to allowed repos.

[pelikhan]

Review the documentation to ensure all repository examples are updated to use only allowed repositories.

[pelikhan]

Keep the repos field in the main JSON key map, but mark it as deprecated.

Ensure all prompts in .github/aw use the new allowed-repos syntax.