When the mouse cursor moves into the whitespace of a line within a
multi-line diagnostic range, the hover popover would previously
disappear. This change adds a check to keep the diagnostic hover visible
if the mouse row intersects with the active diagnostic's range.

Fixes #46841

Release Notes:

- Improved hover behavior for multi-line diagnostics to persist when
hovering over whitespace.


https://github.com/user-attachments/assets/0965cb25-6207-4d4a-9165-0d51157fc6e4