Add alert suggesting that the user switch to a connected account. This
alert is displayed when the popup is opened over an active tab that is
connected to some account, but not the current selected account. The
user can choose to switch to a connected account, or dismiss the alert.
This alert is only shown once per account switch. So if the user
repeatedly opens the popup on a dapp without switching accounts, it'll
only be shown the first time. The alert also won't be shown if the user
has just dismissed an "Unconnected account" alert on this same dapp
and account, as that would be redundant.
The alert has a "Don't show me this again" checkbox that allows the
user to disable the alert. It can be re-enabled again on the Alerts
settings page.
