Update remaining Taquito references of getActiveAccount()

[dsawali]

Since Beacon v4.2.0, getActiveAccount() needs to be replaced by the event subscription as stated in Beacon's migration guide:
https://docs.walletbeacon.io/guides/migration-guide/

In a previous conversation, we have determined together in a video call with Beacon some time ago that Taquito's internal usage of getActiveAccount() to not be intrusive since it's only been used for 'validation' checks when trying to send operations to the wallet. For example: https://github.com/ecadlabs/taquito/blob/master/packages/taquito-beacon-wallet/src/taquito-beacon-wallet.ts#L62

However, for the sake of consistency and reliability, we should update Taquito's Beacon wallet implementation to match the recommended usage from Beacon. That is to use the ACTIVE_ACCOUNT_SET event using the eventSubscribe method instead of getActiveAccount()