add android integration & make iOS API consistent

add pubspec android plugin

update android CMakeLists

add filament android libs for linking

android/CMakeLists.txt

@@ -0,0 +1,21 @@
+cmake_minimum_required(VERSION 3.4.1)  
+
+include_directories(../ios/src)
+include_directories(../ios/include)
+include_directories(src/main/cpp)
+link_directories(src/main/libs/${ANDROID_ABI}) # don't use jniLibs here because we just want to link against these libraries, the actual .so files will be copied by the AAR dependencies
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++17")
+add_library( 
+            filament_interop
+            SHARED
+            src/main/cpp/filament_api.cpp
+            ../ios/src/FilamentViewer.cpp
+            # ../ios/src/Utils.cpp
+            # ../ios/src/HDRLoader.cpp
+            # ../ios/include/common/NioUtils.cpp
+            #../ios/src/morph/GPUMorphHelper.cpp
+        )
+
+
+target_link_libraries(filament_interop -landroid -llog -lfilament-jni -lfilament-utils-jni -lgltfio-jni )
+