Exercism: NotForExactArgs called with multiple args skips auth for no real subcommand

[scottisloud]

NotForExactArgs(argsToSkip ...string) matches when in.CommandArgs equals the provided slice exactly — same length, same values, same order. Calling it with four strings at once:

needsauth.NotForExactArgs("completion", "upgrade", "workspace", "troubleshoot"),

only skips auth when the user literally runs exercism completion upgrade workspace troubleshoot — which is not a valid command. Individual subcommands like exercism completion or exercism workspace do not match and will still prompt for authentication unnecessarily.

Fix: call NotForExactArgs once per subcommand:

needsauth.NotForExactArgs("completion"),
needsauth.NotForExactArgs("upgrade"),
needsauth.NotForExactArgs("workspace"),
needsauth.NotForExactArgs("troubleshoot"),

This ensures each subcommand individually bypasses auth, which is the intended behaviour.