Add the host support to the PowerShell kernel

[daxian-dbw]

Fix #190
Fix #159

Implement the PowerShell host interfaces for the PowerShell kernel, so as to provide a rich interactive experience to the PS kernel.
The light-up features are:

• The general support to foreground and background;
• Write-Host with foreground/background color, and properly deal with -NoNewLine;
• Prompt for input request for Read-Host and Get-Credential;
• Progress rendering similar to the console experience;
• The same concise error view as in the console.

The rich experience is shown as below:

[TylerLeonhardt]

@daxian-dbw Where do we craft StandardOutputValueProduced and send to the client? Does dotnet-interactive do this automatically?

[jonsequitur]

@TylerLeonhardt dotnet-interactive captures console output via the middleware in KernelBase and emits these events for you.

[daxian-dbw]

@TylerLeonhardt It used to be taken care of by individual kernel, but @jonsequitur made a change recently to take care of that in general for all kernels, the relevant code is here:

interactive/Microsoft.DotNet.Interactive/KernelBase.cs

Lines 76 to 91 in 5bce463

	private void AddCaptureConsoleMiddleware()
	{
	AddMiddleware(async (command, context, next) =>
	{
	using var console = await ConsoleOutput.TryCaptureAsync(c =>
	{
	return new CompositeDisposable
	{
	c.Out.Subscribe(s => context.PublishStandardOut(s, command)),
	c.Error.Subscribe(s => context.PublishStandardError(s, command))
	};
	});
	await next(command, context);
	});
	}

[TylerLeonhardt]

Nice. That change flew under my radar. Thanks!

[daxian-dbw]

@TylerLeonhardt Your comments are addressed. Can you please take another look when you get a chance?

[TylerLeonhardt]

one comment, otherwise LGTM - it's pretty wild how much code needs to brought in to truly host PowerShell. I wish we could do something about that but I'm not really sure what.

[daxian-dbw]

Thanks @TylerLeonhardt!
@colombod can you please take a look? We hope to get this in soon 😄

[TylerLeonhardt]

@daxian-dbw any idea if this will work with native executables that accept input/password? Like func new or sudo

[daxian-dbw]

Rebased to resolve conflicts.
@TylerLeonhardt this won't work for native utilities that requests for input/password. Those are native API calls and cannot be handled by the PowerShell host. It's the same as in PowerShell remoting.

[daxian-dbw]

I had a offline discussion with @jonsequitur and @colombod about the concern on the test coverage.
Opened the issue #219 to track adding comprehensive tests for the PS kernel host implementation.

[daxian-dbw]

Rebased the changes to resolve conflict.

[daxian-dbw]

Thanks @jonsequitur! I will get #219 done ASAP.

[jonsequitur]

Thanks to you @daxian-dbw! This is great stuff.