ZegoEffectsEyesBrighteningParam constructor Null safety

1. zego_effects_plugin
2. zego_effects_defines
3. ZegoEffectsEyesBrighteningParam
4. ZegoEffectsEyesBrighteningParam constructor

ZegoEffectsEyesBrighteningParam class

1. Constructors
2. ZegoEffectsEyesBrighteningParam
3. Properties
4. intensity