transcoding: add SimulatedTranscoder to test service

- Add SimulatedTranscoder (which is an upgraded version of
  DummyTranscoder) to allow more testing of the service.

- Add unit test that launches dummy test apps from shell
  to simulate uid policy change.

bug: 154734285
bug: 145233472
test: unit tests

Change-Id: Ic169757d64ad8da7eebd0e1febdcbfb467fe81f4
diff --git a/services/mediatranscoding/tests/TranscodingUidPolicyTestApp/Android.bp b/services/mediatranscoding/tests/TranscodingUidPolicyTestApp/Android.bp
new file mode 100644
index 0000000..95a94fc
--- /dev/null
+++ b/services/mediatranscoding/tests/TranscodingUidPolicyTestApp/Android.bp
@@ -0,0 +1,23 @@
+android_test_helper_app {
+    name: "TranscodingUidPolicy_TestAppA",
+    manifest: "TestAppA.xml",
+    static_libs: ["androidx.test.rules"],
+    sdk_version: "test_current",
+    srcs: ["src/**/*.java"],
+}
+
+android_test_helper_app {
+    name: "TranscodingUidPolicy_TestAppB",
+    manifest: "TestAppB.xml",
+    static_libs: ["androidx.test.rules"],
+    sdk_version: "test_current",
+    srcs: ["src/**/*.java"],
+}
+
+android_test_helper_app {
+    name: "TranscodingUidPolicy_TestAppC",
+    manifest: "TestAppC.xml",
+    static_libs: ["androidx.test.rules"],
+    sdk_version: "test_current",
+    srcs: ["src/**/*.java"],
+}
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