Codechange: Detect and report crashes happening during regression

[glx22]

Motivation / Problem

OpenTTD can crash during regression run but it can be very hard to reproduce if it only happens on CI for other OS than the one used by developer of a PR.

Description

Remove any crash file before running regression, then check no new crash happened.
If there was a crash, then output the crash log so there's at least a stacktrace to get some details.

Test run with assert(false);
Test run with *(volatile uint8_t *)nullptr = 0;

Limitations

Checklist for review

Some things are not automated, and forgotten often. This list is a reminder for the reviewers.

• The bug fix is important enough to be backported? (label: 'backport requested')
• This PR touches english.txt or translations? Check the guidelines
• This PR affects the GS/AI API? (label 'needs review: Script API')
  • ai_changelog.hpp, game_changelog.hpp need updating.
  • The compatibility wrappers (compat_*.nut) need updating.
• This PR affects the NewGRF API? (label 'needs review: NewGRF')
  • newgrf_debug_data.h may need updating.
  • PR must be added to API tracker