no-op: Use helper class to handle pending requests

Pending requests should be updated via a helper class RequestTracker
and stored in a Request wrapper object. This will help out with future
changes to associate each TetheringRequest with it's own
IIntResultListener and make it easier to gate behavior changes.

Bug: 216524590
Test: atest TetheringTest RequestTrackerTest
Change-Id: Ib867e91863bdf618bb0e955eeb529cd132209d77
diff --git a/Tethering/tests/unit/Android.bp b/Tethering/tests/unit/Android.bp
index d0d23ac..ee82776 100644
--- a/Tethering/tests/unit/Android.bp
+++ b/Tethering/tests/unit/Android.bp
@@ -57,6 +57,7 @@
         "mockito-target-extended-minus-junit4",
         "net-tests-utils",
         "testables",
+        "truth",
     ],
     // TODO(b/147200698) change sdk_version to module-current and
     // remove framework-minus-apex, ext, and framework-res