Add unit test init method.

When trying to write some connectionservice unit tests, it became clear
that the mAreAccountsInitialized precondition adds a LOT of overhead
and test scaffolding.  It was easier to just be able to bypass that
in the unit tests.

Test: Added as part of unit test.
Bug: 178649879
Change-Id: Ibed3e69215dad59b252193f701508c18f43b59a2

telecomm/java/android/telecom/ConnectionService.java

@@ -3448,4 +3448,13 @@ public abstract class ConnectionService extends Service {
     public Handler getHandler() {
         return mHandler;
     }
+
+    /**
+     * Sets this {@link ConnectionService} ready for testing purposes.
+     * @hide
+     */
+    @VisibleForTesting
+    public void setReadyForTest() {
+        mAreAccountsInitialized = true;
+    }
 }