Description of changes

This PR attempts to fix c301/grunt-webstore-upload#18 in our repository by using the onError callback defined here. Sometimes the web release fails because it's in pending review status; our ADO task still succeeds because the status is not reported back to grunt.

Tested locally by running:
accessibility-insights-web\drop\extension\dev> npx grunt publish --app-insights-instrumentation-key=test --extension-version=0.0.0 --webstore-app-id=test --webstore-client-id=test --webstore ore-refresh-token=test --force

which ends in:

>> Error while uploading:  Error on uploading (open) with message "Invalid Credentials". Raw response: {"error":{"errors":[{"domain":"global","reason":"authError","message":"Invalid Credentials"...<truncated>

Fatal error: Error on uploading (open) with message "Invalid Credentials"...<truncated> 

which differs from the same scenario run against master:

>> Error while uploading:  Error on uploading (open) with message "Invalid Credentials". Raw response: {"error":{"errors":[{"domain":"global","reason":"authError","message":"Invalid Credentials"...<truncated>

Done, but with warnings.

We want the fatal error so that we can more easily check whether the web release has failed.

Pull request checklist

• Addresses an existing issue: #0000
• Ran yarn fastpass
• Added/updated relevant unit test(s) (and ran yarn test)
• Verified code coverage for the changes made. Check coverage report at: <rootDir>/test-results/unit/coverage
• PR title AND final merge commit title both start with a semantic tag (fix:, chore:, feat(feature-name):, refactor:). Check workflow guide at: <rootDir>/docs/workflow.md
• (UI changes only) Added screenshots/GIFs to description above
• (UI changes only) Verified usability with NVDA/JAWS