Add signal handler on *nix with troubleshooting and stacktrace

[emilk]

Previously a SIGSEGV would just terminate the application,printing segmentation fault and nothing else (on my Mac).

With this PR, you will now get

Rerun caught a signal: SIGSEGV
Troubleshooting Rerun: https://www.rerun.io/docs/getting-started/troubleshooting

followed by a stacktrace.

Tested on:

• Mac
• Linux

Test it like so:

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I've added a line to CHANGELOG.md (if this is a big enough change to warrant it)

[teh-cmc]

Works well on Linux (well, except for stack overflows but I don't think it's worth chasing that considering the insanity it leads to...).

[emilk]

yeah, agree on the stack overflow.

https://github.com/EmbarkStudios/crash-handling is perhaps something worth investigating at some point, but it is quite a complicated beast.