Follow up from #6347

Now

• Generate CLI docs again
• Convert the rest of the CLI to bigcli
• Refactor rest of cli/server_test.go to use "clitest.Start" for better cleanup and error reporting
• Regenerate golden files
• Remove cliflag package
• Verify that cobra is no longer imported
• Removed FormatCobraError
• Ensure Output formatting (e.g. JSON) continues working
• Make sure GIT ASKPASS continues working (environment variable jiu-jitsu)
• Test ReadGitAuthEnv

Later

• Document / Validate YAML works (Add support for YAML options in the server #6707)
• Send back telemetry for each server option, plus how they're set. This makes it easier to make / communicate breaking changes.
• Document how Support Links work in the YAML
• Generate all Deployment setting pages and navigation from Options array
• Format errors in the best possible way
• Complete migration to clitest.Start.
• Remove Option.Default in favor of using whatever is stored in Option.Value. (clibase: use Value instead of Default #6697)
• Allow defining arguments similarly to flags (also remove Middleware concept). (clibase: require structured usage/argument definition #6706)