Add right panel chat timeline (#7112)

Co-authored-by: J. Ryan Stinnett <jryans@gmail.com>

res/css/structures/_RightPanel.scss

@@ -144,6 +144,13 @@ $pulse-color: $alert;
     }
 }
 
+.mx_RightPanel_timelineCardButton {
+    &::before {
+        mask-image: url('$(res)/img/element-icons/feedback.svg');
+        mask-position: center;
+    }
+}
+
 @keyframes mx_RightPanel_indicator_pulse {
     0% {
         transform: scale(0.95);