add download and install of binaryen bin files to install script

[JayJamieson]

I had an issue with building a plugin because binaryen wasn't installed/in my path. I mentioned on discord that having the install include binaryen be a good idea.

Looking for feedback on this.

Didn't find a contribution guide, apologies if I have missed steps in the process.

[bhelx]

Thank you! left a couple comments