Add playback controls to test video in manual app

This allows the user to pause, play, forward etc. the video. The SDK is
also informed when the video pauses or plays.

Bug: 280066444
Test: Build and install the manual test app. Run the command `adb shell
am start -n com.android.sdksandboxclient/.MainActivity --es "video-url"
"<link to video>"`. Click on "Load SDKs" and then click on "Play video".
Test: Check logs to see if the SDK detect user pause/play.

Change-Id: I7a11a8743e4fc105ecde3d80aa168171c4a963ac
1 file changed