feat(SidebarNav): navLink attributes

- optional JS object with valid JS API naming:
- valid attributes: `rel`, `target`, `hidden`, `disabled`, etc...
```json
{
  name: 'Try CoreUI PRO',
  url: 'https://coreui.io/pro/react/',
  icon: 'cui-layers icons',
  variant: 'danger',
  attributes: { target: '_blank', rel: "noopener" },
},
```

Author: xidedix

src/SidebarNav.js

@@ -133,15 +133,22 @@ class AppSidebarNav extends Component {
   // nav link
   navLink(item, key, classes) {
     const url = item.url ? item.url : '';
+    const itemIcon = <i className={classes.icon} />
+    const itemBadge = this.navBadge(item.badge)
+    const attributes = item.attributes || {}
     return (
       <NavItem key={key} className={classes.item}>
-        {
+        { attributes.disabled ?
+            <RsNavLink href={""} className={classes.link} {...attributes}>
+              {itemIcon}{item.name}{itemBadge}
+            </RsNavLink>
+         :
           this.isExternal(url) ?
-            <RsNavLink href={url} className={classes.link} active>
-              <i className={classes.icon} />{item.name}{this.navBadge(item.badge)}
+            <RsNavLink href={url} className={classes.link} active {...attributes}>
+              {itemIcon}{item.name}{itemBadge}
             </RsNavLink> :
-            <NavLink to={url} className={classes.link} activeClassName="active" onClick={this.hideMobile}>
-              <i className={classes.icon} />{item.name}{this.navBadge(item.badge)}
+            <NavLink to={url} className={classes.link} activeClassName="active" onClick={this.hideMobile} {...attributes}>
+              {itemIcon}{item.name}{itemBadge}
             </NavLink>
         }
       </NavItem>

src/SidebarNav.md

@@ -35,7 +35,8 @@ tag | `nav`
     variant: 'info',
     text: 'NEW',
     class: ''                   // optional
-  }
+  },
+  attributes: { target: '_blank', rel: "noreferrer noopener", disabled: false, hidden: false }, // (v2.1.0 up) optional valid JS object with JS API naming
 },
 ````
 - item with `children` array - works like `nav-dropdown-toggle` with `nav-dropdown-items`