Move assets from dash to testdata module

PiperOrigin-RevId: 294241169

library/dash/build.gradle

@@ -33,6 +33,8 @@ android {
         }
     }
 
+    sourceSets.test.assets.srcDir '../../testdata/src/test/assets/'
+
     testOptions.unitTests.includeAndroidResources = true
 }
 

library/dash/src/test/java/com/google/android/exoplayer2/source/dash/manifest/DashManifestParserTest.java

@@ -40,11 +40,11 @@ import org.xmlpull.v1.XmlPullParserFactory;
 @RunWith(AndroidJUnit4.class)
 public class DashManifestParserTest {
 
-  private static final String SAMPLE_MPD = "sample_mpd";
-  private static final String SAMPLE_MPD_UNKNOWN_MIME_TYPE = "sample_mpd_unknown_mime_type";
-  private static final String SAMPLE_MPD_SEGMENT_TEMPLATE = "sample_mpd_segment_template";
-  private static final String SAMPLE_MPD_EVENT_STREAM = "sample_mpd_event_stream";
-  private static final String SAMPLE_MPD_LABELS = "sample_mpd_labels";
+  private static final String SAMPLE_MPD = "mpd/sample_mpd";
+  private static final String SAMPLE_MPD_UNKNOWN_MIME_TYPE = "mpd/sample_mpd_unknown_mime_type";
+  private static final String SAMPLE_MPD_SEGMENT_TEMPLATE = "mpd/sample_mpd_segment_template";
+  private static final String SAMPLE_MPD_EVENT_STREAM = "mpd/sample_mpd_event_stream";
+  private static final String SAMPLE_MPD_LABELS = "mpd/sample_mpd_labels";
 
   private static final String NEXT_TAG_NAME = "Next";
   private static final String NEXT_TAG = "<" + NEXT_TAG_NAME + "/>";