Add support for additional cargo arguments (wasm-pack test)

[zrzka]

💡 Feature description

wasm-pack 0.6 supports additional cargo arguments, but for the build only, not test.

💻 Basic example

I can do:

bash-3.2$ wasm-pack build --target nodejs  --out-dir pkg -- --features disable-wasm-bindings

  [1/10] 🦀  Checking `rustc` version...
  [2/10] 🔧  Checking crate configuration...
  [3/10] 🎯  Adding WASM target...

But I can't do:

bash-3.2$ wasm-pack test --chrome --firefox --headless -- --features disable-wasm-bindings
error: Found argument 'disable-wasm-bindings' which wasn't expected, or isn't valid in this context

USAGE:
    wasm-pack test --chrome --firefox --headless

For more information try --help
bash-3.2$

[fitzgen]

Good news! This was implemented in #530. But its only on master -- will be part of the 0.6.1 release.