Add icons to alerts

app/views/layouts/_flash.html.haml

 -# We currently only support `alert`, `notice`, `success`, 'toast'
+- icons = {'alert' => 'error', 'notice' => 'information-o', 'success' => 'check-circle'};
 .flash-container.flash-container-page.sticky
   - flash.each do |key, value|
     - if key == 'toast' && value
       .js-toast-message{ data: { message: value } }
     - elsif value
       %div{ class: "flash-#{key} mb-2" }
+        = sprite_icon(icons[key], size: 16, css_class: 'align-middle mr-1') unless icons[key].nil?
         %span= value
         %div{ class: "close-icon-wrapper js-close-icon" }
           = sprite_icon('close', size: 16, css_class: 'close-icon')

changelogs/unreleased/icons-to-alerts.yml

+---
+title: Fix aligment for icons on alerts
+merge_request: 22760
+author: Rajendra Kadam
+type: added