cf <unknown> --help exits 0, and usage errors print the whole help before the error #100

cf version: 1.0.0-beta.5, macOS

1. --help on an unknown command exits 0. cf nosuchthing --help; echo $? prints the root help and exits 0, so a script checking whether a command exists gets a false yes.

2. Usage errors print the whole help before the error. cf workers list --nosuchflag prints 28 lines. The actual error is in the last 3:

┌ Error
│ Unknown argument: nosuchflag
└

In a terminal or a CI log, | head shows only help text. Agents reading the first lines miss the error.

Expected: an unknown command exits non-zero even with --help. Usage errors print the error first (or only the error, plus a hint to run --help).

Related: #94 (an aborted delete exits 0).

Found while evaluating cf for a dev workflow: https://github.com/joeblew999/cf-cli-test (FINDINGS.md, findings/).