Add coroutine version of MapsInitializer.initialize()

[bubenheimer]

Is your feature request related to a problem? Please describe.
Need to control Map renderer from coroutines-based environment

Describe the solution you'd like
Would like to use MapsInitializer.initialize(preferredRenderer) from a coroutine. Akin to MapView.awaitMap() to retrieve GoogleMap object. Needs to return the chosen Renderer or throw exception

Describe alternatives you've considered
Roll my own