Feature request: webp encoding

[jimmyff]

Hi, I see you have webp support in the package flutter_image_compress and I realise that the code used in that is ios and android specific however it would be a really useful feature if you were able to implement webp encoding in this package. To my knowledge there is currently no way to encode webp images in native dart.

Thanks

[alann-maulana]

@jimmyff I will implement it soon after package image support webp encoding.

Reference https://github.com/brendan-duncan/image/blob/main/doc/formats.md