Notify the policy when a stylus gesture starts

This will serve as a hint to the policy that a stylus is currently being
used.

Bug: 243005009
Test: atest inputflinger_tests
Change-Id: I2cc187af226fc3a1d4fda36becc280ea7934673a
diff --git a/services/inputflinger/tests/fuzzers/MapperHelpers.h b/services/inputflinger/tests/fuzzers/MapperHelpers.h
index bd81761..64316ba 100644
--- a/services/inputflinger/tests/fuzzers/MapperHelpers.h
+++ b/services/inputflinger/tests/fuzzers/MapperHelpers.h
@@ -315,6 +315,7 @@
         return mTransform;
     }
     void setTouchAffineTransformation(const TouchAffineTransformation t) { mTransform = t; }
+    void notifyStylusGestureStarted(int32_t, nsecs_t) {}
 };
 
 class FuzzInputListener : public virtual InputListenerInterface {
@@ -363,6 +364,7 @@
 
     void updateLedMetaState(int32_t metaState) override{};
     int32_t getLedMetaState() override { return mFdp->ConsumeIntegral<int32_t>(); };
+    void notifyStylusGestureStarted(int32_t, nsecs_t) {}
 };
 
 } // namespace android