Support the ability to start/stop moto server mode through code

Feature Request: Make the server module into a package that can be importable and controlled directly.

Use Case: Spinning up 2 different mock_s3 instances. One with the default aws address and one with a custom DNS endpoint_url passed into boto3.

I have only been able to run 2 separate mocks of the same service via the standalone server with different ports. It would be helpful if moto had a way to programmatically start/stop the standalone server mode natively with python. Currently the only way I have nicely been able to accomplish this is by starting the server in a subprocess.

def _moto_server_process(service, host, port):
    cmd = ['moto_server', service, '-p', str(port), '-H', host]
    return subprocess.Popen(cmd, stdout=subprocess.PIPE,
                            stderr=subprocess.STDOUT)

[thehesiod]

btw I created this: https://gist.github.com/thehesiod/2e4094a1db1190f7e122e7043f1973a0

[bblommers]

Moto 3.0.6 now includes a way to start the MotoServer programmatically. See the documentation here: http://docs.getmoto.org/en/latest/docs/server_mode.html#start-within-python

It is still in beta while we collect feedback, so if you find any bugs or improvements, feel free to open a new issue!