Debug and fix memory leaks

New runtimes work differently and are not well tested yet for memory leaks. We are working on fixing issues anything we find.

• When a java object is finally freed in Java, we notify the JS side to free the JS counterpart. At this time, the Java object is held weakly in Java too using a WeakReference. While the Java object is weakly held, the WeakReference is strongly kept in a HashMap never getting removed. In this PR we release the WeakReferences too on GC event ensuring that all memory is reclaimed. Fixed in https://github.com/NativeScript/napi-android/commit/5e48302fc0eeab63eae6935e864de36d25100e2c
• Investigate Java Interface Implementation leaking on JS Side

issue 中没有指定文件或测试。先查看所引用的 commit，然后调查 JS 侧残留的 Java Interface Implementation 泄漏；完成的标准是修复所列出的泄漏并回收内存。