Use custom host for run-android

[abzainuddin]

When running react-native run-android --help, there is an option to specify the port with --port.
Is it also possible to specify the host?

Use case: I'm using https://github.com/budtmo/docker-android to run an android avd inside a docker container, but would like to run the js server on another container.

[thymikee]

cc @grabbou you were interested about use cases for custom host

[grabbou]

Please see this #195. I don't think how --host flag would resolve your case (do you even need it?)

Please comment in that issue so that we can decide to drop it or not.