Handle per-step errors and returning error data

[jpwilliams]

Summary

Adds handling and returning of per-step errors instead of the current error flow of intentionlly throwing to trigger a 500 Internal Server Error.

Checklist

• [x] Added a docs PR that references this PR
• [x] Added unit/integration tests
• [x] Added changesets if applicable
• [x] inngest/inngest#843 must be shipped and upstreamed to Cloud before we merge
• [x] Ensure error serialization always creates a StepError for step errors

Related

• Relies on inngest/inngest#1058
• inngest/website#655

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 969bfe8d85d953429bba0e533bda8658baffba63

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

| Name | Type | | ------- | ----- | | inngest | Minor |

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[inngest-release-bot]

A user has added the prerelease/inngest label, so this PR will be published to npm with the tag pr-411. It will be updated with the latest changes as you push commits to this PR.

You can install this prerelease version with:

npm install inngest@pr-411

The last release was built and published from 969bfe8d85d953429bba0e533bda8658baffba63.