ZegoEffectsForeheadShorteningParam constructor Null safety

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

ZegoEffectsForeheadShorteningParam class

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