fix(cli): report mistyped subcommand before options

[vianmangal]

Summary

• defer group-level unknown option validation until Commander resolves a child command
• report a mistyped subcommand before any options that follow it
• preserve unknown-option errors for valid leaf commands and groups without a subcommand

Why

Command groups validated unknown options before their default action could identify an invalid subcommand. As a result, elastic stack es serch --index my-index reported --index as unknown instead of identifying the serch typo.

Testing

• npm test
• npm run test:lint
• npm run test:spdx
• npm run test:notice
• manually verified mistyped-subcommand, valid-command/invalid-option, and group/invalid-option cases

Closes #501

[margaretjgu]

See inline comments.