Add-ons Alert Improvements by Xon 2.13.1

• Fix unsummarizing a summary alert would cause an internal server error if a rare deadlock occurred
• Fix possible deadlock interrupting the process which expires too-old alerts

• Require StandardLib v1.22.0+
• Fix bulk alert 'mark read' would fail if there was no unread alerts on the current page but the user had unread alerts
• Fix changing Unread alert icon/Recent alert icon did not trigger XF2.3 font-awesome icons to be consistently added
• Rework how alert read status icon is added to an alert
  • Add Just read alert icon style properties to style a just read alert icon and give it a tooltip phrase.
    • This icon is disabled by default for new installs. Upgrades will inherit Unread alert icon flag to enable this functionality per-style
  • Update various alert icons to match between XF2.2 and XF2.3, and rename icon style property names to be less confusing
    • "Unread" alert icon is now fas fa-star (solid star)
    • "Just toggled read" alert icon is now fas fa-star-exclamation (solid star with an exclamation in the middle)
    • "Recent read alert" icon is now far fa-star (hollow star)

• Fix edge case where clicking 'mark read' on an alert or the 'all' alerts button would miss updating alerts
• Add confirmation prompt when clicking "mark read" for marking alerts as read.
• Add per-user "Prompt on bulk mark read" option. Controlled by the global "Mark-read prompt opt-out" option.