Fix up pipeline stage result setting and exception handling

[andrew-m-leonard]

Fixes #1068

Problem:

• Because for several sub-jobs like "tests", we use propagate: false, the job result does not set the stage result, we currently only set the overall build result. (Note: We want propagate: false so we can run all the tests and then report all the failures, rather than exit the job at the very first failure)

This PR fixes:

• Ensure all sub-jobs called within "stages" also set the stage result
• Tidy up several catch(Exception) clauses that swallow exceptions, and were not setting overall build result to FAILURE
• Add missing "sign verification" stage

Fixed tests:

• Various x64Linux forced failures/aborts, showing correct SmokeTest stage results:
  
• Various Mac stages, aborted/failed, all showing correct Stage results:
  

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[andrew-m-leonard]

run tests

[sxa]

I'm not an expert on these pipelines, but if this definitely works I'm delighted to approve it (And it'll be fairly obvious soon if there are any problems with it I expect)

[sxa]

Adding Sophia as a potential reviewer as she was involved in the issue referenced in the description.

[sophia-guo]

LGTM

[eclipse-temurin-bot]

 PR TESTER RESULT 

❎ Some pipelines failed or the job was aborted! ❎
See the pipeline-build-check below for more information...