Additional CTS test for pinned stack

- Verify that pinned stack is front stack.
- Verify that there is only one resumed activity in the system.
- Verify that pinned activity window is the front window.
- Verify that pinned stack isn't focused stack and is for always focuable activity.
- Verify that pinned activity isn't focused activity and is for always focuable activity.
- Verify that pinned activity isn't resumed activity and is for always focuable activity.
- Verify launch on pinned stack @hidden API functionality.

Also, made the host side test class more modular.

Bug: 19225708
Bug: 26273032
Change-Id: Iab88787cba786737598eb7ea4137e067c6ec5f48
diff --git a/hostsidetests/services/activitymanager/app/AndroidManifest.xml b/hostsidetests/services/activitymanager/app/AndroidManifest.xml
index 32dba48..995649f 100755
--- a/hostsidetests/services/activitymanager/app/AndroidManifest.xml
+++ b/hostsidetests/services/activitymanager/app/AndroidManifest.xml
@@ -16,7 +16,8 @@
  -->
 
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    package="android.server.app">
+          xmlns:androidprv="http://schemas.android.com/apk/prv/res/android"
+          package="android.server.app">
 
     <application>
         <activity android:name=".TestActivity"
@@ -32,6 +33,23 @@
                 android:supportsPictureInPicture="true"
                 android:exported="true"
         />
+        <activity android:name=".AutoEnterPipActivity"
+                  android:resizeable="true"
+                  android:supportsPictureInPicture="true"
+                  android:exported="true"
+        />
+        <activity android:name=".AlwaysFocusablePipActivity"
+                  android:resizeable="true"
+                  android:supportsPictureInPicture="true"
+                  androidprv:alwaysFocusable="true"
+                  android:exported="true"
+        />
+        <activity android:name=".LaunchIntoPinnedStackPipActivity"
+                  android:resizeable="true"
+                  android:supportsPictureInPicture="true"
+                  androidprv:alwaysFocusable="true"
+                  android:exported="true"
+        />
     </application>
 </manifest>