Added missing selected listener to the new playback fragments

BaseOnItemViewSelectedListeners were missing from the new
PlaybackFragment and PlaybackSupportFragment. This listener is invoked
once the focus changes across different items of a PlaybackControlsRow or
external rows of a playback fragment.
Also created test suites for both PlaybackFragment and
PlaybackSupportFragment with selected and clicked listener tests.

Fixes: 33779048
Test: ./gradlew support-leanback-v17:connectedCheck
-Pandroid.testInstrumentationRunnerArguments.class=android.support.v17.leanback.app.PlaybackFragmentTest
./gradlew support-leanback-v17:connectedCheck
-Pandroid.testInstrumentationRunnerArguments.class=android.support.v17.leanback.app.PlaybackSupportFragmentTest

Change-Id: Ia6ee8e14b19f7ff81d8c1cfb87d8e3fca84f963c
11 files changed