resourcemanager: move common code into different source.

This change moves all the common code into a separate source
to enable extenstion of resource manager service implementation.
And also, a new creation function is added to enable the same.

Bug: 294886363
Test: atest android.media.misc.cts.ResourceManagerTest
      atest android.media.misc.cts.ResourceManagerMultiTest
      /data/nativetest64/ResourceManagerService_test/ResourceManagerService_test
      /data/nativetest64/ResourceObserverService_test/ResourceObserverService_test
Merged-In: I70f4776979104f1468e2791bb8e977ab85d9676a
Change-Id: I70f4776979104f1468e2791bb8e977ab85d9676a
diff --git a/media/libmediaplayerservice/tests/DrmSessionManager_test.cpp b/media/libmediaplayerservice/tests/DrmSessionManager_test.cpp
index 30f6a91..6da8e31 100644
--- a/media/libmediaplayerservice/tests/DrmSessionManager_test.cpp
+++ b/media/libmediaplayerservice/tests/DrmSessionManager_test.cpp
@@ -148,8 +148,8 @@
 class DrmSessionManagerTest : public ::testing::Test {
 public:
     DrmSessionManagerTest()
-        : mService(::ndk::SharedRefBase::make<ResourceManagerService>
-            (new FakeProcessInfo(), new FakeSystemCallback())),
+        : mService(ResourceManagerService::Create(
+                  new FakeProcessInfo(), new FakeSystemCallback())),
           mDrmSessionManager(new DrmSessionManager(mService)),
           mTestDrm1(::ndk::SharedRefBase::make<FakeDrm>(
                   kTestSessionId1, mDrmSessionManager)),