[library list] added 'plus' icon to the toggle of the dropdown menus at the end of the headings (#7400)

frontend/src/pages/shared-with-all/index.js

@@ -250,10 +250,11 @@ class SharedWithAll extends React.Component {
         <div className="main-panel-center">
           <div className="cur-view-container">
             <div className="cur-view-path">
-              <h3 className="sf-heading m-0">
+              <h3 className="sf-heading m-0 d-flex align-items-center">
                 {gettext('Shared with all')}
                 {canAddPublicRepo &&
                 <SingleDropdownToolbar
+                  withPlusIcon={true}
                   opList={[
                     { 'text': gettext('Share existing libraries'), 'onClick': this.onSelectRepoToggle },
                     { 'text': gettext('New Library'), 'onClick': this.onCreateRepoToggle }