Cursor stuck around attachment when pressing up arrow

The cursor is unable to get to the line above and keeps jumping around the attachment.

##### Steps to Reproduce

1. Open https://trix-editor.org/.
2. Delete all the default text.
3. Press enter.
4. Press a.
5. Insert a PDF (or anything else that doesn't show a thumbnail) attachment.
7. Press up arrow repeatedly.


##### Details

* Trix version: 2.0.4
* Browser name and version:
* Brave (Verze 1.46.144 Chromium: 108.0.5359.128 (Oficiální sestavení) (arm64))
* Chrome (Verze 106.0.5249.61 (Oficiální sestavení) (arm64))
* Edge (Verze 106.0.1370.52 (Oficiální build) (arm64))
* Safari (Verze 16.1 (18614.2.9.1.12))
* Operating system: macOS 13.0.1

It worked fine in Firefox (108.0.1 (64-bit)).

Start by reproducing the issue at https://trix-editor.org/ using the listed steps, especially with an attachment that has no thumbnail. Trace the editor's cursor movement when pressing the up arrow around that attachment. Done means the cursor can reach and remain on the line above, while the existing behavior continues to work in the listed browsers.

Written by the indexing model from the issue text.