List: implement right icon for list items.

src/widgets/List.css

@@ -26,13 +26,20 @@
   outline: 0;
 }
 
-.ListItem .ListIcon {
+.ListItem .ListIconLeft {
   margin-left: 5px;
   margin-right: 20px;
   margin-top: 8px;
   margin-bottom: 8px;
 }
 
+.ListItem .ListIconRight {
+  margin-left: auto;
+  margin-right: 5px;
+  margin-top: 8px;
+  margin-bottom: 8px;
+}
+
 .ListItem-Item:hover {
   background-color: rgba(0, 0, 0, 0.1);
   cursor: pointer;

src/widgets/List.tsx

@@ -85,7 +85,11 @@ export const ListItem = pure((_props: any) => {
   } = _props;
 
   const leftIconHolder = (leftIcon) ? (
-    <div className="ListIcon">{leftIcon}</div>
+    <div className="ListIconLeft">{leftIcon}</div>
+  ) : undefined;
+
+  const rightIconHolder = (rightIcon) ? (
+    <div className="ListIconRight">{rightIcon}</div>
   ) : undefined;
 
   let textHolder = primaryText;
@@ -105,6 +109,7 @@ export const ListItem = pure((_props: any) => {
       {leftIconHolder}
       {textHolder}
       {children}
+      {rightIconHolder}
     </ListItemRaw>
   );
 });