ZegoEffectsFaceShorteningParam constructor Null safety

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

ZegoEffectsFaceShorteningParam class

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