feat: resourceLoader decorator needs to support multiple loaders for asset

[zhuxudong]

Is your feature request related to a problem? Please describe.
For hdr assets, I want to be able to parse into Texture2D or TextureCube,but i can't now.

@resourceLoader(AssetType.HDR, ["hdr"])
class HDRLoader extends Loader<TextureCube> {}

Describe the solution you'd like

@resourceLoader(AssetType.HDR, LoaderType.TextureCube,["hdr"])
class HDRCubeLoader extends Loader<TextureCube> {}

@resourceLoader(AssetType.HDR, LoaderType.Texture2D, ["hdr"])
class HDR2DLoader extends Loader<Texture2D> {}

engine.resourceManager.load({
   type:AssetType.HDR,
   loaderType: LoaderType.Texture2D, 
   url: "***.hdr"
})