Make the robo tests work in command line with the android build

The make files in libs were mising:
ifeq (,$(ONE_SHOT_MAKEFILE))
    include $(call all-makefiles-under,$(LOCAL_PATH))
endif

Also androidx.arch.core_core-testing isn't available anymore, but after
including androidx.arch.core_core-runtime and
androidx.arch.core_core-common, I only had to clone the tiny class
InstantTaskExecutorRule

Also added an NPE fix in MediaSourcesLiveDataTest

Test: make -j64 RunCarMediaCommonRoboTests
make -j64 RunCarArchCommonRoboTests

Change-Id: I0539442a923bf998220200ee0ef45239227e236f
diff --git a/car-arch-common/Android.mk b/car-arch-common/Android.mk
index 6fd8d5c..712f170 100644
--- a/car-arch-common/Android.mk
+++ b/car-arch-common/Android.mk
@@ -43,3 +43,7 @@
 LOCAL_RESOURCE_DIR := $(LOCAL_PATH)/res
 
 include $(BUILD_STATIC_JAVA_LIBRARY)
+
+ifeq (,$(ONE_SHOT_MAKEFILE))
+    include $(call all-makefiles-under,$(LOCAL_PATH))
+endif