Allow noir-libs to be a dependency of external Noir Contracts

[iAmMichaelConnor]

Currently, to use our standard library of Aztec contract helper functions and structs, you need to develop your contract inside aztec-packages, by specifying the relative path in the contract's Nargo.toml.

Alternatively, Nargo also allows a GitHub url of the dependency to be provided, but the Nargo.toml of the dependency must be at the top level of the repo (whereas our noir lib is currently nested inside yarn-project/).

Corresponding issue created in Noir-Lang here.

[dbanks12]

Assigning to @sirasistant as @iAmMichaelConnor and @LeilaWang requested.

[sirasistant]

If we finally go with noir-compiler for compilation, we should support git dependencies on it. Shouldn't be too bad 🤞

[sirasistant]

PR in noir noir-lang/noir#2436