[BUG] file based key panics

Current Behavior

When i have a flow.json with a file based key this code panics

//accounts here is accounts.Accounts that is gotten from flowkit.State
	for _, account := range acct {
	  account.Key.ToConfig().PrivateKey.PublicKey(),
        }

see source here https://github.com/bjartek/overflow/blob/a97abbd88656a7910be110e3a8226a80afcdf582/state.go#L446

Expected Behavior

I expect to get the public key, the key need here though is to just create a new user using the key that is provided in flow.json. Maybe a method to return a accounts.PublicKey from an account.Accounts would be better?

Steps To Reproduce

1. create a flow.json with a file based key
2. use https://github.com/bjartek/aether

Environment

- OS: mac

What are you currently working on that this is blocking?

Aether

Start at state.go line 446 and reproduce the panic with a flow.json containing a file-based key, using aether as described. Trace how flowkit.State provides accounts.Accounts and how the key is converted, then verify that the file-based key no longer panics and supports retrieving the public key for the stated use case.