SceneReader sets contentSize by canvasSize.

We could not get the canvas size of the scene which created on CocosStudio.

Thanks to this commit, we can get scene's canvas size by Node::getContentSize()

```cpp
auto scene = cocos2d::cocostudio::SceneReader::getInstance()->createNodeWithSceneFile("Scene.json");
int width = scene->getContentSize().width;
int height = scene->getContentSize().height;
cocos2d::log("canvasSize = %d, %d", width, height);
```
Fixed LabelAtlas opacity do not change when setting parent node's opacity
Add CameraTest、OBBTest and related lua bindings
Merge branch 'v3' of https://github.com/cocos2d/cocos2d-x into v3_3D
Merge branch 'v3' into v3_fixGLProgramCrash
fix button title only content size issue
Fixed FileUtils::removeFile doesn't work on iOS
fix cocostudio include path
fixed compile error
fix compile error for macro redefinition
remove texture unit 4-7, only 0 -3 is reserved
Merge pull request #7979 from giginet/scene-reader-canvas-size

SceneReader sets contentSize by canvasSize.
Merge branch 'v3' into v3_fixGLProgramCrash
Merge pull request #8610 from andyque/fixCocostudioIncludePath

fix cocostudio include path
add 'static' for global function
Merge pull request #8604 from samuele3hu/v3_3D

Add CameraTest、OBBTest and related lua bindings
Merge pull request #8606 from andyque/fixButtonContentSize

fix button title only content size issue
[ci skip] Update CHANGELOG
Merge pull request #8611 from dabingnn/v3_fixGLProgramCrash

V3 fix gl program crash
[ci skip] Update CHANGELOG