update dependencies

[joshuahannan]

This PR updates the dependencies to the latest cadence, flow-go-sdk, emulator, and flow-go

The cadence update required the cadence string function to be changed to support an error return value
The flow-go update required that we do not use the service account for any of the tests because it has conflicting storage paths with the tests

Also added an upgrade to the LockedTokens contract to allow extra TokenHolder objects to be created after the first and a transaction to create an extra one for a new account, along with a test

[Kay-Zee]

So in the case of someone calling createNodeStaker after this upgrade, this will just get over-written, right?

[joshuahannan]

yeah, but I can actually just remove the lines in createNodeStaker because they aren't needed anymore

[Kay-Zee]

            // Create a new staker proxy that can be accessed in transactions
            self.nodeStakerProxy = LockedNodeStakerProxy(tokenManager: self.tokenManager)

            // create a new delegator proxy that can be accessed in transactions
            self.nodeDelegatorProxy = LockedNodeDelegatorProxy(tokenManager: self.tokenManager)

Is the major change that i'm concerned with, and looks good to me.

Not sure about the dependency updates though