Create a LegacyNetwork key provider in Acquia Connector

Problem/Motivation

With the move to Key for all things key storage, we need to move the hard coded key fetching from our eventsubscriber ‘FromAcquiaCloud’ into a key provider that fetches the following data from settings if we’re on acquia hosting.

Data: ah_network_identifier, ah_network_key, ah_application_uuid

Use most of the logic in the event provider for this provider, including checking for AH specific environment variables to verify we’re on hosting. You’ll notice in the eventsubscriber that we override the network settings with state. don’t do this. We will have a different ticket centered around a KeyResolver that will determine whether we fetch from state or directly from hosting.

With this provider, you should be able to create a new Key which will fetch the above data automatically. Create a test ensuring the provider is working when on hosting (mock the AH env vars) and returning NULL when not.