stop using System.CommandLine types that aren't public anymore

[adamsitnik]

First of all, I've tried to eliminate the need of using the Help APIs that were made internal. For example, for options that were shared between multiple commands, we were using WithHelpDescription to set a custom description. The fix was to simply have a dedicated copy of given option for every command, with a unique description. This had a side effect of generating completions with descriptions that are more accurate (hence the test file update).

When I got to the point where it was not worth the effort, I've followed the plan we have established offline: just copy pasting the internal types here. I've added them to the Microsoft.TemplateEngine.Cli, as it defines an interface that is using HelpContext and is being used by the other projects that customize help. That was quite straightforward, all I needed was to update the license header, namespaces and fix some code analysis issues like leading whitespace etc.

Context: dotnet/command-line-api#2563

[adamsitnik]

This is not something new, rather a re-use of a workaround from the past:

sdk/src/Cli/Microsoft.TemplateEngine.Cli/Commands/create/InstantiateCommand.Help.cs

Lines 19 to 20 in 7a4d106

	private static Lazy<ResourceManager> _resourceManager = new(
	() => new ResourceManager("System.CommandLine.Properties.Resources", typeof(System.CommandLine.Symbol).Assembly));

[MiYanni]

General changes look fine. Just pointed out a few random things to look into.

[MiYanni]

So, this is a bit odd...
A func is a method delegate. Why do you return a method call that creates a delegate? Just return a method itself. Meaning:

Suggested change

	public static IEnumerable<Func<HelpContext, bool>> GetLayout()
	{
	yield return SynopsisSection();
	yield return CommandUsageSection();
	yield return CommandArgumentsSection();
	yield return OptionsSection();
	yield return SubcommandsSection();
	yield return AdditionalArgumentsSection();
	}
	public static IEnumerable<Func<HelpContext, bool>> GetLayout()
	{
	yield return SynopsisSection;
	yield return CommandUsageSection;
	yield return CommandArgumentsSection;
	yield return OptionsSection;
	yield return SubcommandsSection;
	yield return AdditionalArgumentsSection;
	}

And change them to be the method signature. For example:

        public static Func<HelpContext, bool> SynopsisSection() =>
            ctx =>
            {
                ctx.HelpBuilder.WriteHeading(LocalizationResources.HelpDescriptionTitle(), ctx.Command.Description, ctx.Output);
                return true;
            };

Becomes:

        public static bool SynopsisSection(HelpContext context)
        {
            context.HelpBuilder.WriteHeading(LocalizationResources.HelpDescriptionTitle(), context.Command.Description, ctx.Output);
            return true;
        };

[adamsitnik]

I agree that it's far from perfect, but it's a copy of System.CommandLine source code and I would prefer to introduce as few changes as possible (in order to make it easier to sync changes if needed in the future)

[MiYanni]

nit: If-Else is redundant.

Suggested change

	if (symbol is Option or Command)
	{
	return GetOptionOrCommandRow();
	}
	else if (symbol is Argument argument)
	{
	return GetCommandArgumentRow(argument);
	}
	else
	{
	throw new NotSupportedException($"Symbol type {symbol.GetType()} is not supported.");
	}
	if (symbol is Option or Command)
	{
	return GetOptionOrCommandRow();
	}
	if (symbol is Argument argument)
	{
	return GetCommandArgumentRow(argument);
	}
	throw new NotSupportedException($"Symbol type {symbol.GetType()} is not supported.");

[MiYanni]

nit: Redundant else.

[MiYanni]

? What are these numbers?