Add-ons Alert Improvements by Xon 2.12.2

• When the user's alert count is non-zero, the alert-popup is forced to fetch unread alerts first, and if no unread alerts are discovered this indicates the user's alert count is out-of-sync and needs to be reset.

• Add explain text to the "Use custom" value for "Alerting Preferences" per-user option
• Add "[Alert Improvements] Can customize advanced alert preferences" permission to control is a user can change the following per-user preferences: "Alerts page options"/"Alert pop-up options"/"Alerts summarize threshold"
  Permission granted to Registered user group by default

• Fix incorrect phrase for default alert type in admincp
• Fix new alert types could be opted out by default instead of opt-in
• Fix user's alert preferences may not save with some configurations
• On alert opt-out list; only render "reset" checkbox for non-default values