If we want to support dss' spells-mainnet, we'll need to support lib linking.

Problem

1. We call into_inner here: https://github.com/gakonst/foundry/blob/master/forge/src/multi_runner.rs#L61
2. Then we call into_bytes: and then https://github.com/gakonst/ethers-rs/blob/4c677933ce4407fb1307f9077aefc31b9e811cdb/ethers-solc/src/config.rs#L260
3. But into_bytes returns None for unlinked objects
4. So we'll need to somehow call link before doing the deployment step.

Suggested Solution

1. We should provide a manual way for somebody to link to an already deployed library
2. We should auto-detect if there's library dependencies, deploy all the libraries first, get their addresses, and then link them in all the bytecodes necessary.