ic-ref tests should show trapping instruction locations on trap

[osa1]

Currently it's incredibly difficult to debug RTS or code generator issues because the error messages do not help, they simply say "canister trapped". Here's an actual example:

ingress Err: IC0502: Canister 75hes-oqbaa-aaaaa-aaaaa-aaaaa-aaaaa-aaaaa-q trapped: heap out of bounds

I previously spent days trying to debug these errors in #1750, and I'm doing the same now in #1931.

If ic-ref showed the trapping instruction's location, as an offset in the Wasm module, that'd help immensely. Some of the bugs that I wasted hours debugging would take a few minutes.

Since we'll be doing more work on the RTS (for garbage collection and probably other stuff too) and code generator I think it makes sense to invest some time into making ic-ref show trapping instruction locations.

I already started hacking on winter for this. This is an issue to keep track of the progress.

Note that the fix for this will be in winter and maybe ic-ref, not in Motoko. I'm creating the issue here as the end goal is to help with Motoko development, but let me know if I should move this to winter's or ic-ref's Github repo.

(We previously briefly discussed this on slack)

[nomeata]

Fixed in 81962fc