Creates an instance of the Fastly LaunchDarkly client.

Applications should instantiate a single instance for the lifetime of a request. The client will begin attempting to connect to the configured Fastly KV as soon as it is created. To determine when it is ready to use, call LDClient.waitForInitialization.

Important: Do not try to instantiate LDClient with its constructor (new LDClient()/new LDClientImpl()/new LDClient()); the SDK does not currently support this.