TaskRunner: move implementation to cpp

Test: hidl_test
Bug: 35710429
Change-Id: If5b6ece1bc08e27bb818eec0eae33c4a842106ad
diff --git a/base/TaskRunner.cpp b/base/TaskRunner.cpp
index 33117e7..782b40b 100644
--- a/base/TaskRunner.cpp
+++ b/base/TaskRunner.cpp
@@ -43,6 +43,10 @@
     }
 }
 
+bool TaskRunner::push(const Task &t) {
+    return (mQueue != nullptr) && (!!t) && this->mQueue->push(t);
+}
+
 } // namespace details
 } // namespace hardware
 } // namespace android