Add the ability to save and receive files as Blob or File W3C in WasmJs

[apolostudio]

Basically that, right now only bytearray is supported and if i want to transform blob into bytearray i have to add a lot of boilerplate code. Also i could be made via PlatformFile and add a function to convert blob, bytearray, File W3C to PlatfromFile. Then i should only have to pass the platfrom file to save() function. Note that File W3C inherits blob class

[vinceglb]

Hi @apolostudio! Thanks for creating this issue!

It's a really good idea to support File, Blob and ByteArray for web targets!

I'll try to support them in the next version of FileKit!