[CI] Improve overall PR Tests time

[radical]

Reduces CI time from ~24mins to ~15mins.

[tests] Split NewUpAndBuildSupportProjectTemplates

The number of tests have multiplied in this class, and it takes ~14 mins on github
actions to run them. Split them up so they can run in parallel and the
overall run time can come down.

[Copilot]

Pull Request Overview

This PR refactors the NewUpAndBuildSupportProjectTemplatesTests class by extracting a shared protected method into an abstract base class and splitting the various template configurations into separate derived test classes so they can run in parallel.

• Introduces NewUpAndBuildSupportProjectTemplatesBase (abstract) with CanNewAndBuildActual
• Creates one derived test class per template variant (NUnit, XUnit v2/v3/v3MTP, MSTest, etc.)
• Removes the monolithic [Theory] with many MemberData entries and spreads them across multiple classes

Comments suppressed due to low confidence (4)

tests/Aspire.Templates.Tests/NewUpAndBuildSupportProjectTemplatesTests.cs:8

• [nitpick] The base class name ends with Base but doesn’t clearly signal it’s for tests. Consider renaming to NewUpAndBuildSupportProjectTemplatesTestsBase for consistency with test naming conventions.

public abstract class NewUpAndBuildSupportProjectTemplatesBase(ITestOutputHelper testOutput) : TemplateTestsBase(testOutput)

tests/Aspire.Templates.Tests/NewUpAndBuildSupportProjectTemplatesTests.cs:64

• [nitpick] Type names with underscores diverge from .NET PascalCase conventions. Rename NUnit_NewUpAndBuildSupportProjectTemplatesTests to something like NUnitNewUpAndBuildSupportProjectTemplatesTests.

public class NUnit_NewUpAndBuildSupportProjectTemplatesTests : NewUpAndBuildSupportProjectTemplatesBase

tests/Aspire.Templates.Tests/NewUpAndBuildSupportProjectTemplatesTests.cs:64

• [nitpick] There is significant duplication across the multiple derived test classes differing only by their MemberData argument. Consider parameterizing these variants (e.g., via a single [Theory] with combined MemberData or code generation) to reduce boilerplate.

public class NUnit_NewUpAndBuildSupportProjectTemplatesTests : NewUpAndBuildSupportProjectTemplatesBase

tests/Aspire.Templates.Tests/NewUpAndBuildSupportProjectTemplatesTests.cs:71

• Attribute parameters must be compile-time constants; verify that the C# collection-expression syntax (["aspire-nunit", ""]) is valid here. If not, switch to an explicit new object[]{ ... } initializer.

    [MemberData(nameof(TestDataForNewAndBuildTemplateTests), arguments: ["aspire-nunit", ""])]