feat(clients): Add Lockbox icon, fix Pontoon icon (#5959), r=@vbudhram

app/images/icon-service-lockbox.svg

@@ -0,0 +1 @@
+<svg id="Layer_3" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32"><style>.st0{fill:#505050}</style><path class="st0" d="M25.2 3.3H6.8c-3 0-5.5 2.5-5.5 5.5v14.7c0 3 2.5 5.5 5.5 5.5h18.4c3 0 5.5-2.5 5.5-5.5V8.8c0-3.1-2.5-5.5-5.5-5.5zM27 23.5c0 1-.8 1.8-1.8 1.8H6.8c-1 0-1.8-.8-1.8-1.8V8.8C5 7.8 5.8 7 6.8 7h18.4c1 0 1.8.8 1.8 1.8v14.7z"/><path class="st0" d="M14.9 15.6c-1.6-.6-2.4-2.4-1.8-4s2.4-2.4 4-1.8c1.6.6 2.4 2.4 1.8 4-.3.9-1 1.5-1.8 1.8l1.4 5.8c.1.6-.2 1.1-.8 1.3H14.5c-.6 0-1-.5-1-1v-.3l1.4-5.8z"/></svg>

app/images/icon-service-pontoon.svg

@@ -1 +1 @@
-<?xml version="1.0" encoding="UTF-8" standalone="no"?><svg width="22" height="28" viewBox="0 0 22 28" xmlns="http://www.w3.org/2000/svg"><title>Slice 1</title><g fill="none" fill-rule="evenodd"><path d="M4 4h14v16H4V4zm0 16h4v8H4v-8z" fill="#EDEDED"/><path fill="#505050" d="M8 8h6v8H8zM8 20h4v8H8v-8zm14 0v4H12v-4h10zM0 0h4v28H0V0zm18 0h4v20h-4V0zM4 0h14v4H4V0z"/></g></svg>
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32"><path d="M9.1 6h14v16h-14V6zm0 16h4v8h-4v-8z" fill="#ededed"/><path d="M13.1 10h6v8h-6v-8zm0 12h4v8h-4v-8zm14 0v4h-10v-4h10zM5.1 2h4v28h-4V2zm18 0h4v20h-4V2zm-14 0h14v4h-14V2z" fill="#505050"/></svg>

app/styles/modules/_settings.scss

@@ -661,6 +661,11 @@ section.modal-panel {
   &[data-name='Pontoon'] {
     background-image: url('/images/icon-service-pontoon.svg');
   }
+
+  &[data-name='Lockbox'],
+  &[data-name='Lockbox iOS'] {
+    background-image: url('/images/icon-service-lockbox.svg');
+  }
 }
 
 .client-webSession {