Feature request: Several separators in toolbars

### Is your feature request related to a problem?

I don't like the removal of separators in Firefox version 89.

### The solution I'd like

1. Separator between “Shield” and “Lock” buttons (In address bar),
2. Separator between “URL” and “Lock” button (In address bar),
3. Separator between extensions **address bar** buttons ([Flagfox](https://addons.mozilla.org/en-US/firefox/addon/flagfox/), [Tab Stash](https://addons.mozilla.org/en-US/firefox/addon/tab-stash/), etc…) and reader view button (In address bar),
4. Separator between overflow menu button and application menu button (In navigation bar).

Notes:
— All separators should be configurable in `about:config`.
— If I hover the mouse on “Lock”, or “Shield” buttons, or if I click on these buttons, then the first mentioned separator should disappear (Like in pre-89 photon Firefox).
— For the third separator, I think extensions items in ADDRESS BAR and not in toolbar (The extensions buttons that were in “Page actions” menu, but now they are in address bar right next to “Reader view” button). I am writing this note, because one person in Bugzilla didn't understood what I said, he thought that I am thinking the new unified extensions menu.

### Screenshots or video

_No response_

### Alternatives I've considered

_No response_

### Additional context

_No response_

No file or test is named in the issue. Start by locating the styles or configuration handling Firefox address-bar and navigation-bar controls, then verify the four requested separator positions, their about:config configurability, and the specified hover or click behavior.

Written by the indexing model from the issue text.