Use VSTest (TRX) result and attach diff snapshot files

[compulim]

This PR branch is under microsoft because we need to test it in VSTS. We can't test fork on VSTS.

Fixes #2897.

Changelog Entry

Added

• Resolves #2897. Moved from JUnit to VSTest reporter with file attachments, by @compulim in PR #2990

Description

Today, we use a custom service, namely webchat-curator, to store our snapshots.

Since Azure DevOps support file attachment for test result, we can move away from our custom service and use Azure DevOps.

We need to move from JUnit reporter to VSTest/TRX reporter, and add custom code to inject the snapshot file.

https://docs.microsoft.com/en-us/azure/devops/pipelines/tasks/test/publish-test-results?view=azure-devops&tabs=yaml#attachments-support

Specific Changes

• Use jest-trx-results-processor
• Configure the TRX processor to emit <FileResults>
• After merging this PR, we need to update Azure DevOps

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• Testing Added
  • No tests added, can't automate testing for infrastructure

[corinagum]

Build succeeded on Azure... merging.