Add ProjectOptions.Interactive so that callers can specify that project evaluation can be interactive

[jeffkl]

Fixes #8523

Context

When a build happens the BuildParameters object passes along the Interactive property when creating ProjectInstance objects. During evaluation, the Evaluator then sets the built-in MSBuildInteractive property to true and the SDK resolver context is also set.

However, when you create an instance of a ProjectInstance object via the ProjectInstance.FromFile(string, ProjectOptions) method, there is no way to indicate that the evaluation should be interactive.

Changes Made

This change adds a new Interactive property to the ProjectOptions object. The value is passed to the evaluator and the MSBuildInteractive MSBuild property is now set.

I implemented this for:

• ProjectInstance.FromFile(string, ProjectOptions)
• ProjectInstance.FromProjectRootElement(ProjectRootElement, ProjectOptions)
• Project.FromFile(string, ProjectOptions)
• Project.FromProjectRootElement(ProjectRootElement, ProjectOptions)
• Project.FromXmlReader(XmlReader, ProjectOptions)

Testing

I added unit tests for all affected methods by testing what happens when Interactive is set to true or false. When the value is true, it is expected that the MSBuildInteractive MSBuild property is set, otherwise the property value should be an empty string.

Notes

• I broke up the commits separately in case we don't want to touch Project (although it was trivial to implement).
• The last commit migrates ProjectInstance_Internal_Tests to Shouldly, commit ff9398d46008b1e2389dafb083cf6b86fb40eedb has a simpler diff showing the added tests.

[jeffkl]

Its difficult to tell in this diff but this is where the interactive flag is passed to the evaluator.

[Forgind]

LGTM!

[rainersigwald]

I support doing Project too.