This CL allows users to set control categores in MediaRouter.
With this, media apps can seamless transfer feature w/o using
Mediarouter2.
This Cl also adds test to ensure that control categories are sent to
media router manager properly.
MediaRouter2ServiceImpl maintains a list of MediaRouter clients to save
their control categories and send: them to media router manager.
Test: atest mediaroutertest
Change-Id: I80dad04053200119ceb54f63d2cef0b06bac8e3d
2f43fd6c57