Stake account should assert on state

[mcintyre94]

As currently written, the stake account tests do not include any assertions if the state is not initialized or stake:

    const assertions: StakeAccountAssertion[] = [];

    if (
      simulatedAccount.accountType === 'initialized' ||
      simulatedAccount.accountType === 'stake'
    ) {
      // add assertions
    }

    let builder = assertStakeAccountMulti(umi, {
      targetAccount: publicKey(simulatedAccount.address),
      logLevel,
      assertions,
    });

Assuming a sophisticated attacker can control the simulation result, they could provide a state that is not one of these. The actual transaction could then steal eg the withdraw authority, which there would be no assertion for.

I think we should protect against this by asserting the state is as expected from the simulation result, failing the transaction if the stake account is put into an unexpected state.