Replace BlackBox functions vendoring from backend to library

[kobyhallx]

As a Developer
I would like to be able to resolve BlackBox functions from library linked to execution
so that I am no tightly coupled with backend providing those (currently through Barretenberg backend).

AC:

1. acvm-backend-barretenberg should be replaced while BlackBox functions are resolved with a library providing those.

[TomAFrench]

We could approach this in two ways:

• Move the barretenberg wasm binary from acvm_js to another crate which gets included in the acvm crate by default
• Bring the barretenberg wasm binary up to nargo and then pass it in to ACVM similarly to how we do now but as a BlackBoxSolver rather than as a Backend.

The first is preferable but will need testing to ensure that this works across targets nicely. The second is definitely possible but prevents encapsulation of this barretenberg wasm.

[TomAFrench]

This can be closed as acvm-blackbox-solver exposes these functions.