Add tests for custom tools (used to generate API docs)

[IEvangelist]

Summary

This draft PR preserves the tool generator test additions separately from release/13.2 after the direct cleanup commit that removed them from the release branch.

Included here

• tests/AtsJsonGenerator.Tests
• tests/PackageJsonGenerator.Tests
• .github/workflows/tools-tests.yml
• Related solution and ignore-file wiring

Notes

• release/13.2 was updated directly to remove these tests.
• This PR is intentionally kept separate so the test additions are not lost.
• Do not merge this back into release/13.2 unless you intentionally want to reintroduce the tests there or retarget the PR.

Validation

• dotnet test tests/PackageJsonGenerator.Tests/PackageJsonGenerator.Tests.csproj --configuration Release --nologo
• dotnet test tests/AtsJsonGenerator.Tests/AtsJsonGenerator.Tests.csproj --configuration Release --nologo

[Copilot]

Pull request overview

This PR reintroduces and preserves the tool generator test projects and their CI wiring on a separate branch, after they were removed from release/13.2, so the test additions aren’t lost.

Changes:

• Adds new xUnit test projects for PackageJsonGenerator and AtsJsonGenerator, including helper tests and temporary-assembly/test-data scaffolding.
• Introduces a dedicated GitHub Actions workflow to run these tool generator tests and publish TRX/binlog artifacts with a step summary.
• Wires the new test projects into the repo solution and adjusts .dockerignore to exclude tests from Docker build context.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/scripts/Write-TestSummary.ps1	New PowerShell helper to aggregate TRX results into a GitHub Step Summary (with optional artifact link).
tests/PackageJsonGenerator.Tests/PackageJsonGeneratorTests.cs	Adds coverage for package.json metadata output, enum sealing behavior, XML docs list handling, and LF normalization/no-op rewrites.
tests/PackageJsonGenerator.Tests/PackageJsonGeneratorHelperTests.cs	Adds unit tests for helper methods like raw GitHub URL building and line parsing.
tests/PackageJsonGenerator.Tests/PackageJsonGenerator.Tests.csproj	New test project targeting net10.0 and referencing the PackageJsonGenerator tool project.
tests/PackageJsonGenerator.Tests/GlobalUsings.cs	Adds global xUnit using for the test project.
tests/AtsJsonGenerator.Tests/AtsTransformerHelperTests.cs	Adds targeted tests for ATS transformer helper formatting/normalization behavior.
tests/AtsJsonGenerator.Tests/AtsJsonGeneratorTests.cs	Adds end-to-end-ish TransformFile tests including base-model dedupe and LF normalization/no-op rewrites.
tests/AtsJsonGenerator.Tests/AtsJsonGenerator.Tests.csproj	New test project targeting net10.0 and referencing the AtsJsonGenerator tool project.
tests/AtsJsonGenerator.Tests/GlobalUsings.cs	Adds global xUnit using for the test project.
Aspire.Dev.slnx	Includes the new test projects in the repo solution structure.
.github/workflows/tools-tests.yml	Adds a CI workflow to restore/run both test projects, upload results, and generate a summary.
.dockerignore	Excludes test content from Docker build context.

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[eerhardt]

I wish there was a built-in task for this. Seems odd that we need to implement it ourselves.