Spike monorepo

[garethfuller]

We are building up abstract hooks and utilities that may be valuable to the wider Balancer and DeFi ecosystem. However, it's difficult to externalise our tooling because to do so would require extracting code into separate repos and publishing on npm to then import into the frontend again. This introduces painful context switching and maintenance that makes it impossible to manage more than a couple of repos/packages alongside the frontend.

If we move to a monorepo we can first migrate isolated code into packages without needing to publish to npm and also use it seamlessly within the frontend. Eventually we can start to publish the most useful pieces of our app.