KnownResourceStates.TerminalStates should include KnownResourceStates.Hidden #6468
Description
The KnownResourceStates class includes members for known resource states including 'Running', 'Exited', etc., and a field TerminalStates that's contains all known states considered terminal, i.e. once resources move to that state they won't move to any other state.
The TerminalStates field should include the KnownResourceStates.Hidden value as we still have some resources that end up in that state, e.g. parameters. If one is writing test code today that waits for all resources to reach the KnownResourceStates.Running state or any terminal state before continuing, they can't simply rely on the KnownResourceStates.TerminalStates member to do so, e.g. the following code will never complete if there are any resources that move to the KnownResourceStates.Hidden state:
public static Task WaitForResources(this DistributedApplication app, IEnumerable<string>? targetStates = null, CancellationToken cancellationToken = default)
{
targetStates ??= [KnownResourceStates.Running, ..KnownResourceStates.TerminalStates];
var applicationModel = app.Services.GetRequiredService<DistributedApplicationModel>();
var resourceNotificationService = app.Services.GetRequiredService<ResourceNotificationService>();
return Task.WhenAll(applicationModel.Resources.Select(r => resourceNotificationService.WaitForResourceAsync(r.Name, targetStates, cancellationToken)));
}