For mobile (#6523)

* ['notice' popover, 'all notice' dialog] fixup for mobile

* ['Files' page] fixed library icon size for mobile

* ['settings' page] fixup for 'Email notification'

* ['my libs'] fixed 'star/unstar', 'share', 'delete'

* ['deleted repos' dialog] modified column width of the table for mobile

* ['share' dialog] modified 'link details' panel for mobile

* [side panel resizer] removed it for mobile

* [group/department, shared with all] fixed the operation menu for mobile

* ['dir view'] don't offer 'repo history' page for mobile

* ['help'] fixup for page with large images, for mobile

- fixup for http://127.0.0.1:8000/help/drive_client_2.0_for_windows_10/
  (in mobile, the content of it overflowed to the right, and was cut off)

* ['file view'] removed 'history' page for mobile

* ['markdown file view'] removed 'history' page for small screen, mobile

* ['dir view'] added a gray layer to close the 'file/folder tree' panel in mobile

* ['dir view'] fixup for the 'path' bar in mobile

* ['dir view', 'shared dir view'] don't display the 'tag list' in root for mobile

frontend/src/components/toolbar/dir-operation-toolbar.js

@@ -289,7 +289,14 @@ class DirOperationToolbar extends React.Component {
     } else {
       content = (
         <Dropdown isOpen={this.state.isMobileOpMenuOpen} toggle={this.toggleMobileOpMenu}>
-          <DropdownToggle tag="span" className="sf2-icon-plus mobile-toolbar-icon" />
+          <DropdownToggle
+            tag="div"
+            role="button"
+            className="path-item"
+          >
+            {this.props.children}
+            <i className="sf3-font-down sf3-font ml-1 path-item-dropdown-toggle"></i>
+          </DropdownToggle>
           <DropdownMenu>
             {canUpload && (
               <DropdownItem onClick={this.onUploadFile}>{gettext('Upload')}</DropdownItem>