Update forms security page

[bjarnef]

At the moment with Umbraco v8.6.3 (and latest changes in v8/contrib branch) and Umbraco Forms: 8.4.0 the security page under users section doesn't quite match the rest of the backoffice UI.

Some changes that could be done:

• Use <umb-editor-view>, <umb-editor-header>, <umb-editor-container>, <umb-box-content> and <umb-editor-footer> like this: https://github.com/umbraco/Umbraco-CMS/blob/v8/contrib/src/Umbraco.Web.UI.Client/src/views/languages/edit.html#L5
  This would also ensure the header looks right and the button is at bottom.

• Use <umb-toggle> for the settings: Manage Forms, Manage Workflow, Manage Data Sources, Manage PreValue Sources or maybe <umb-toggle-group>.

• Use <umb-checkbox> for Has Access checkbox

• Highlight of user node work, but not for super user (it might be because super user has id -1, which I think is the same root level has).

[nul800sebastiaan]

Thanks @bjarnef, I've put it on the list of things to look into when we're ready to work on ui/ux issues.