parse stderr for ASAN for libfuzzer targets

[bmc-msft]

Summary of the Pull Request

Adds parsing stderr to look for ASAN style logs during libfuzzer crash reporting

PR Checklist

• Applies to work item: Go language support #118
• CLA signed. If not, go over here and sign the CLI.
• Tests added/passed
• Requires documentation to be updated
• I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #xxx

Info on Pull Request

This PR does two things:

1. Adds parsing of stderr to libfuzzer targets
2. Standardizes run_cmd onto our own Output

This doesn't implement stderr parsing for non-libfuzzer tasks, nor does it attempt to parse the output if you used a debugger. Eventually, it would be good to normalize our debugger wrappers to include the same Output but that is out of scope for this PR.

Validation Steps Performed

1. Run standard libfuzzer binary and see crash reports
2. Run a test with a go-fuzz based binary and see crash reports