Action & Filter name consistency

Check use of action/filter prefixes

- `view_admin_as` everywhere for global filters
- `vaa_view_admin_as` everywhere for global actions
- `vaa_admin_bar` Toolbar related actions & filters
- `_view_admin_as` for internal filters not to be used outside of the plugin
- `_vaa_view_admin_as` for internal actions not to be used outside of the plugin