Musl compatible protoc-gen-js

Please provide a musl compatible protoc-gen-js.

I know it's possible because I've been able to build the project in Alpine Linux, but a release tar like the ones we already have for Glibc would be much more convenient. Or maybe a static build that works on both.

[dibenede]

In principle, we are not opposed to this, but this work would be blocked on protoc providing build support (likewise for static compilation). It looks like they have a similar issue open here: protocolbuffers/protobuf#7040.

I'll poke the thread to see if they have any updates.