Add `device.crash` event semantic convention

[bidetofevil]

Adding the definition for an Event that models a crash in the mobile app. There are still some open questions to be worked out regarding naming and the specific event attribute definitions, but I want to put the draft changes in a PR to get further feedback from a larger group, having done so already via a doc with some other folks in the mobile community.

The PR is not ready to merging right now. I will make it a non-draft when it is.

Merge requirement checklist

• [ ] CONTRIBUTING.md guidelines followed.
• [ ] Change log entry added, according to the guidelines in When to add a changelog entry.
  • If your PR does not need a change log, start the PR title with [chore]
• [ ] schema-next.yaml updated with changes to existing conventions.

[lmolkova]

/cc @open-telemetry/semconv-mobile-approvers

[tonzhan2]

This looks like a great start. I'm curious as to what some examples of crashes could look like in this format. Such as an Android jvm crash. Obviously most of it will be in the body, so I guess of that format is still tbd. Could be useful nonetheless to have some examples of crashes that use this formatting