First pass for Dialer onboarding flow

* Add OnboardingActivity that controls the onboarding the UI
ensuring that the user grants the necessary permissions before
the Dialer can start.
* Add first pass (no graphics, eyeballed measurements) for the
screens that request for default dialer as well as permissions
* OnboardingActivity is not actually launched at this moment - will
be tied in to the various Dialer activities in a follow up CL.
* Add tests for logic that controls the display of the screens in
anticipation of future additions to the onboarding flow.
* Add mockito library to DialerTests's Android.mk

Bug: 24270592

Change-Id: I00d0f75edaecaa85042b136b0d830b5fbb3a0a73
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index e58d2ce..94333eb 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -244,6 +244,12 @@
         <activity android:name="com.android.contacts.common.vcard.ExportVCardActivity"
                   android:theme="@style/BackgroundOnlyTheme"/>
 
+        <activity
+            android:name="com.android.dialer.onboard.OnboardingActivity"
+            android:theme="@style/OnboardingFlowTheme"
+            android:screenOrientation="nosensor"
+            android:exported="false" />
+
         <service
             android:name="com.android.contacts.common.vcard.VCardService"
             android:exported="false"/>