enhanced javascript plugins

- added expand & collapse method in PushMenu
- added expandSidebar & sidebarButtonSelector option in Treeview
- updated docs

docs/javascript/push-menu.md

@@ -60,6 +60,8 @@ Example: `$(document).on('shown.lte.pushmenu', handleExpandedEvent)`
 | Method | Description
 |-|-
 |toggle | Toggles the state of the menu between expanded and collapsed.
+|collapse | Collapses the sidebar menu.
+|expand | Expands the sidebar menu
 {: .table .table-bordered .bg-light}
 
 Example: `$('[data-widget="pushmenu"]').PushMenu('toggle')`