Implementation of API Discovery interfaces

-- Interface DiscoveryInterface method
     PendingOperation findServices(ServiceType serviceType, FindCallBack findCallBack, Options options, Filter filter)
-- Interface FindCallBack method
     void onError(DOMError error)
-- Interface PendingOperation method
     void cancel()

This is part of a joint commit together with webinos-jsonrpc2.

Jira issue: WP-703
Jira issue: WP-684
Jira issue: WP-688
Jira issue: WP-301