Replace `allow_save_diagnostics_data_on_crash` with `debug` enum

[cortadocodes]

Feature request

Use Case

Provide a debug enum that replaces allow_save_diagnostics_data_on_crash that allows parents to specify at question time:

• Debugging off all the time
• Debugging on if there's a crash
• Debugging on all the time

Current state

It's either on for a crash or fully off.