DetailedList widget will attempt to render multiple lines of title/subtitle text

[freakboy3742]

Describe the bug

If you define a DetailedList widget whose title and/or subtitle includes newlines, some platforms will render multiple lines, and some will not.

Steps to reproduce

Add a DetailedList with data items that include newlines in the title and subtitle.

Expected behavior

The rendering should be consistent across all platforms, displaying only the content up to the first newline.

This should be implemented at time of rendering, splitting the title/subtitle text at the first newline, and only rendering the first line.

Screenshots

Via beeware/briefcase#1600, the rendering on Android:

Environment

• Operating System: Android; possibly others.
• Python version: All
• Software versions:
  • Toga: 0.4.1

Logs

No response

Additional context

No response