add username to UserMenu props

src/containers/CourseHeader/AuthenticatedUserDropdown/__snapshots__/index.test.jsx.snap

@@ -14,7 +14,9 @@ exports[`Header AuthenticatedUserDropdown component snapshot 1`] = `
     <UserAvatar
       username="test-username"
     />
-    <UserMenu />
+    <UserMenu
+      username="test-username"
+    />
   </Dropdown>
 </Fragment>
 `;

src/containers/CourseHeader/AuthenticatedUserDropdown/index.jsx

@@ -20,7 +20,7 @@ export const AuthenticatedUserDropdown = ({
     </a>
     <Dropdown className="user-dropdown">
       <UserAvatar username={username} />
-      <UserMenu />
+      <UserMenu username={username} />
     </Dropdown>
   </>
 );