PLT-6614 - Mentions badge styling and dropdown icon style (#6426)

* Mentions badge styling and dropdown icon style

* PLT-6134 - Fixing emoji picker border in RHS

webapp/sass/components/_mentions.scss

@@ -9,6 +9,21 @@
     z-index: 10;
 }
 
+.mention-badge {
+    background-color: #777;
+    border-radius: 10px;
+    color: #fff;
+    display: inline-block;
+    font-size: 12px;
+    font-weight: bold;
+    line-height: 1;
+    min-width: 10px;
+    padding: 3px 7px;
+    text-align: center;
+    vertical-align: middle;
+    white-space: nowrap;
+}
+
 .mentions__name {
     @include clearfix;
     cursor: pointer;

webapp/sass/layout/_sidebar-left.scss

@@ -53,7 +53,7 @@
         padding: 1em 1em 0;
     }
 
-    .badge {
+    .mention-badge {
         background-color: $primary-color;
         position: absolute;
         right: 10px;

webapp/sass/layout/_team-sidebar.scss

@@ -54,7 +54,7 @@
                         width: 31px;
                     }
 
-                    .badge {
+                    .mention-badge {
                         font-size: 10px;
                         position: absolute;
                         right: -6px;