BUG-870: Added support for discovering YangModuleInfo via ServiceLoader.

  - Added ModuleInfoBackedContext which provides
     -  GeneratedClassLoadingStrategy which supports proactive search
     -  Creation of SchemaContext based on registered YangModuleInfo

Change-Id: I890c275031151b874b42b4e46bee4edcfce595ec
Signed-off-by: Tony Tkacik <ttkacik@cisco.com>
(cherry picked from commit 03417a177eee5ca63fe14b5a5e75e7b104979a83)
Merge "BUG-870: Added support for discovering YangModuleInfo via ServiceLoader." into stable/hydrogen