Visible input border suppressed separator even when it draws no line
toward list section (bottom in default layout, top in reverse, vertical).
Suppress only when input border has a line on the list side; otherwise
fall through to adjacent section check.
- Requires header window to have content before treating it as facing
section; hasHeaderWindow returns true with empty header when input
border is visible
- Extract inputBorderFacesList and resolveInputBorderShape shared by
options and terminal
- Add tests for separator suppression rules
Junegunn Choi
7fe4831be6