Fix: nonce discrepancy issues when there's a pending txn

[borislav-itskov]

Change log:

• rename nonce to currentAccountNonce in estimate.ts for more readability. EstimateResult should always return the current nonce, or the one the user will commit to in case of a execute() authrorization
• if there's a discrepancy in the accountOp.nonce and the (outcome.nonce - 1), we 1) return an error in signAccountOp and do not allow the user to sign 2) set the found nonce from the estimation in accountOp as the true nonce and wait for simulation & estimation reruns

[Ivshti]

lgtm