Unify `admin_bar.html` and the revert feature of `viewpage.html`

*NOTE*: "revert" is currently being called by Infogami, so that may require special consideration, and make it poorly suited to being a good first or second issue.

### Describe the problem that you'd like solved

We have an "admin bar" with some options in it, then a separate html file with separate styling for the revert button, when we may want to have them together.

### Proposal & Constraints

During today's design call we briefly mentioned extending `admin_bar.html` (and the associated styling for `admin-bar`) by adding the `revert` button to it.

To this end we'd want to:
1. rename `admin_bar.html` and the `admin-bar` CSS class to something like `advanced_options.html` and `advanced-options` in CSS; and
2. ensure proper permissions/scoping for the buttons in this unified view.

Here's how the "revert" button looks on `Author`, pages, `List` pages, and probably anywhere else, aside from `Work` and `Edition` pages, which u sed to look this way, but at some point 'broke':

Here's how the admin bar looks, while also viewing a page which can be reverted:

Based on the call today, we'd want to the `revert` button inside the admin bar, to the right of `View Book on Archive.org` (which we may also want to remove, but that may be a separate discussion).

### Additional context

The complicating factor here is that `viewpage.html` seems to be called by Infogami, so we'd want to be extra sure nothing is breaking from changes to `viewpage.html`, because it's Infogami that is making `viewpage.html` automagically render where it can be used.

### Stakeholders