fix: `--verbose` option not working for `run-ios`

[liamjones]

Fixes #1391

Summary:

This commit implements a workaround to get the verbose option working again on run-ios. It not working is caused by the fact that the root command has a verbose option too. This 'steals' it from the the run-ios sub-command in commander 2.x. See https://github.com/react-native-community/cli/issues/1391#issuecomment-813078097 for more information.

Test Plan:

Added unit tests for the new code. Testing run directly looked like it was going to be a hassle so I exported attachCommand so I could test it directly, I hope that's okay.