feat: add child-process-gone event to app

[miniak]

Description of Change

Allows reporting utility process issues in application telemetry. Is also replaces the gpu-process-crashed event. It gives more information about what happened to the process similar to render-process-gone.

Examples:

• child-process-gone { type: 'Utility', reason: 'killed', name: 'Network Service' }
• child-process-gone { type: 'Utility', reason: 'killed', name: 'Audio Service' }
• child-process-gone { type: 'GPU', reason: 'killed' }

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• tests are changed or added
• relevant documentation is changed or added
• PR title follows semantic commit guidelines
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.
• This is NOT A BREAKING CHANGE. Breaking changes may not be merged to master until 11-x-y is branched.

Release Notes

Notes: Added utility-process-gone event to app.

[MarshallOfSound]

This is awkward naming because of the child_process module in node. Is there another name we can use for this that wouldn't conflict with that existing concept

[nornagon]

IMO this is a different enough context that the namespace collision doesn't bother me, and it's valuable i think to match Chromium's naming where possible.

[jkleinsc]

The API WG approved this PR at our July 13th 2020 meeting

[release-clerk]

Release Notes Persisted

Added utility-process-gone event to app.