Renames to better align with use and existing naming patterns.
Using 'connection' to avoid confusion as to control flow or
roles. (A connection is direct from SystemUI --> App process)
IScrollCaptureClient -> IScrollCaptureConnection
IScrollCaptureController -> IScrollCaptureCallbacks
Test: atest FrameworksCoreTests:ScrollCaptureConnectionTest \
FrameworksCoreTests:ScrollCaptureTargetResolverTest \
ScrollCaptureTest
Change-Id: I9afd33109f6718b61d172ce3e4b3bb5d71a2897e