Listbox Browser focus rings plus other minor visual fixes

# Bug Report
Currently, our listbox browser has a lot of "extra" focus rings that make it confusing to use and very noisy. The majority of these bugs impact this component's usability while some are visual improvements. The usability bugs are must-have and the visual bugs are nice to haves.

[Please see Confluence doc for all screenshots](https://aclgrc.atlassian.net/wiki/spaces/UX/pages/662410769/Listbox+Browser+Component+Review+11+22+2019).

## Usability bugs

### Both Single and Multi-select
1. Extra container focus
2. Auto-focus first item

### Single select
7. Don’t jump selections

### Multi-select
8. What appears to be 2 focus on elements

## Visual bugs

### Both Single and Multi-select
3. Selected options background grey
4. Back button
5. Trashbin

### Single select
6. Hover style on >

### Multi-select
9. Hover style on >

The issue targets the Listbox Browser component and lists separate single- and multi-select focus/visual problems. No specific files, tests, or commands are provided. Start by locating the Listbox Browser implementation and its styling in the repo, then reproduce each numbered behavior (focus rings, auto-focus, selection jump, duplicate focus, hover/background issues). Consider it done when each listed item is corrected in the relevant mode(s) and the component behavior matches expected usability.

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