Let ctrl+click in vscode take you to the line number

SUSHI currently outputs line number information in this format:

```
File: /home/vadi/Programs/MRI-Scheduling/input/fsh/diagnosticreport.fsh
Line: 16 - 19
```

This is very human-friendly and nice! But ctrl+clicking on diagnosticreport.fsh in VSCode only takes you to the file, and not the line number as well. If you have a several hundred line file, this slows things down a bit

If the output could be changed to:

```
File: /home/vadi/Programs/MRI-Scheduling/input/fsh/diagnosticreport.fsh:16
Line: 16 - 19
```

This would be both human-friendly and editor friendly - ctrl+clicking on the file would take you to the line where the problem starts automatically.

Does this sound like a good idea?

Search the repository for the current "File:" output and inspect the code that formats diagnostic locations. Update the output to include the starting line after the file path while preserving the existing human-readable line range, then verify that the generated path is suitable for VSCode ctrl+click navigation.

Written by the indexing model from the issue text.