Allows it to set into the state arbitrary code at an arbitrary account.
This will make it very easy to patch contracts that contain immutables.
Then we can patch the contracts to have different immutables without
needing to update the proxies and worry about that.

We can also cheat the impl of the multisig to be a call forwarder so
that we do not need to cheat so many storage slots and forget about
particular slots.