Simplified and more efficient version of D14666 where a `Check Alias` button is added which leverages the existing registration input field and validation logic.
Results from the check are rendered via UI notifications.
Clicking Check Alias on an alias with pending registrations
{F7088795}
Clicking Check Alias on an alias with no pending registrations
{F7088797}
When an invalid alias is entered, the Check Alias button is also disabled
{F7088798}