Add dump to Input Classifier

Currently, the InputClassifier stage that is positioned between
InputReader and InputDispatcher is not accounted for when doing a
'dumpsys input'. But that stage may contain important information about
the operation and the InputClassifier HAL. Add the dump(..) command to
both InputClassifier and MotionClassifier.

Test: dumpsys input and inspect the resulting text
Next, crash the InputClassifier HAL (killall android.hardware.input.classifier@1.0-service
Then again 'dumpsys input' to check that the HAL status is 'not
responding'
Bug: 117935272
Change-Id: Ie7ddca2e355e094f93236a9bc667faad7a99ee70
diff --git a/services/inputflinger/BlockingQueue.h b/services/inputflinger/BlockingQueue.h
index b892120..c9eb683 100644
--- a/services/inputflinger/BlockingQueue.h
+++ b/services/inputflinger/BlockingQueue.h
@@ -80,6 +80,16 @@
         mQueue.clear();
     };
 
+    /**
+     * How many elements are currently stored in the queue.
+     * Primary used for debugging.
+     * Does not block.
+     */
+    size_t size() {
+        std::scoped_lock lock(mLock);
+        return mQueue.size();
+    }
+
 private:
     size_t mCapacity;
     /**