Add the `etc/bindings-all.py` script to orchestrate bindings generation
Add the `etc/bindings-all.py` script to orchestrate bindings generation

The `bindings-all.py` script will make sure that you don't accidentally try and
use DEBUG bindings for a non-DEBUG build or vice-versa. It orchestrates all of
building, regenerating and testing new SpiderMonkey bindings.

jdm/rust-mozjs,jdm/rust-mozjs,jdm/rust-mozjs,jdm/rust-mozjs,servo/rust-mozjs,nnethercote/rust-mozjs,servo/rust-mozjs,nnethercote/rust-mozjs,jdm/rust-mozjs,nnethercote/rust-mozjs,nnethercote/rust-mozjs,nnethercote/rust-mozjs,servo/rust-mozjs,servo/rust-mozjs