Add a test to ensure all playground app manifests are up-to-date

[eerhardt]

We should keep the playground app manifests up to date as we make changes. That way people make sure they do it on the changes that change the manifests.

Having this would have caught bugs like Fix Azure Functions Role Assignments to Host Storage (dotnet/aspire#8290).

cc @captainsafia @radical @davidfowl @mitchdenny @sebastienros

[radical]

Would this test essentially be - generate the manifest with --publisher manifest --output-path aspire-manifest.json, and compare with the aspire-manifest.json next to the project?

[eerhardt]

Yep - or we could do it like https://github.com/azure/azure-sdk-for-net/ does things - run eng/refreshManifests.ps1 and do a git diff. If the diff is clean, then it passes. If any file changed, fail.

[radical]

And this isn't specific to a sdk version, correct? So I can use whatever latest 9.0.x version might be there?

[eerhardt]

Correct - this shouldn't matter what version of the SDK being used.