[Blazor] Bring-in sdk style tests support for build and "publish" for Maui apps

Bring in tests similar to the ones that we have in https://github.com/dotnet/sdk for gestures like build and publish.

Ideally we want to have some coverage for this on CI that allows us to exercise the build/publish pipeline on each platform and perform some basic build checks, like, does the content exist inside the package and so on, to quickly validate that we are generating the correct output and preventing build regressions.