Allow ngrok configuration to be passed in

[dsmwong]

Hi,

It would be good to be able to add additional options to allow ngrok configuration to be passed in. The following use cases for --ngrok action

pass in subdomain into ngrok so it generate a consistent URI for ngrok
pass in user specified configuration file instead of using ~/.ngrok2/ngrok.yml for configration. This will allow project specific ngrok configuration to be set.

[welcome]

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