Add MetricsProcessor to calculate metrics stats

This CL adds MetricsProcessor class to calculate metrics stats
for both device tests and host tests.

Test: atest MicrodroidBenchmarks
Change-Id: I4f742d6800f14c857a5d0e0718e09870e8ca6547
diff --git a/tests/helper/Android.bp b/tests/helper/Android.bp
index f8dcef7..6d769e6 100644
--- a/tests/helper/Android.bp
+++ b/tests/helper/Android.bp
@@ -9,8 +9,14 @@
 }
 
 java_library_static {
+    name: "MicrodroidTestHelper",
+    srcs: ["src/java/com/android/microdroid/test/common/*.java"],
+    host_supported: true,
+}
+
+java_library_static {
     name: "MicrodroidDeviceTestHelper",
-    srcs: ["src/java/com/android/microdroid/**/*.java"],
+    srcs: ["src/java/com/android/microdroid/test/*.java"],
     static_libs: [
         "androidx.test.runner",
         "androidx.test.ext.junit",