Add audio+video testbinsrc based tests.

medias/defaults/testbin/audio+video.stream_info

+<file duration="20000000000" frame-detection="1" uri="testbin://audio,samplesperbuffer=1024,num-buffers=862+video,num-buffers=600,pattern=ball,motion=sweep,flip=true" seekable="true">
+  <streams caps="none">
+    <stream type="video" caps="video/x-raw" id="videotestsrc_stream_0"/>
+    <stream type="audio" caps="audio/x-raw" id="audiotestsrc_stream_0"/>
+  </streams>
+</file>

testsuites/validate.testslist

@@ -756,3 +756,16 @@ validate.http.transcode.to_vorbis_and_vp8_in_webm.vorbis_vp8_1_webm
 ~validate.rtsp2.playback.switch_audio_track.tron_en_ge_aac_h264_ts
 ~validate.rtsp2.playback.switch_subtitle_track.test5_mkv
 ~validate.rtsp2.playback.switch_subtitles.test5_mkv
+validate.testbin.playback.change_state_intensive.audio+video
+validate.testbin.playback.fast_forward.audio+video
+validate.testbin.playback.play_15s.audio+video
+validate.testbin.playback.reverse_playback.audio+video
+validate.testbin.playback.scrub_forward_seeking.audio+video
+validate.testbin.playback.seek_backward.audio+video
+validate.testbin.playback.seek_forward.audio+video
+validate.testbin.playback.seek_with_stop.audio+video
+validate.testbin.transcode.to_mp3_and_h264_in_mp4.audio+video
+validate.testbin.transcode.to_rawaudio_and_prores_in_quicktime.audio+video
+validate.testbin.transcode.to_vorbis_and_h264_in_mkv.audio+video
+validate.testbin.transcode.to_vorbis_and_theora_in_ogg.audio+video
+validate.testbin.transcode.to_vorbis_and_vp8_in_webm.audio+video