Better DX around failing on startup

[trevor-scheer]

Right now, serverless gateway applications are stuck with "startup but fail on every request" in the case that the gateway fails to load its schema, so the process doesn't actually die. This could be improved by installing a startupDidFail plugin by default or at least documenting it as a recommendation in the README.

Update: it's been brought to my attention that Lambda can in fact handle async initialization and that it might be able to move to a standard await apolloServer.start() mode of operation vs the less optimal startInBackgroundHandlingStartupErrorsByLoggingAndFailingAllRequests() method.