Implement remote home controls data source

Implements a remote data source for the information home controls dreams
needs, which will query the remote service in SYSTEM_USER.

Flag: com.android.systemui.home_controls_dream_hsum
Bug: com.android.systemui.home_controls_dream_hsum
Test: atest HomeControlsRemoteProxyTest
Test: atest RemoteHomeControlsDataSourceDelegatorTest
Change-Id: I97c5b455debfce0499daf78b1510df946c771f60