move IValueDescriptor to System.CommandLine.NamingConventionBinder

[adamsitnik]

It was way easier than I expected, mostly because at the end of the day the crucial part of the code was casting IValueDescriptor to Argument and Symbol:

command-line-api/src/System.CommandLine.NamingConventionBinder/SpecificSymbolValueSource.cs

Lines 21 to 40 in d18f598

	var specificDescriptor = ValueDescriptor;
	switch (specificDescriptor)
	{
	case Option option:
	var optionResult = bindingContext?.ParseResult.FindResultFor(option);
	if (optionResult is not null)
	{
	boundValue = optionResult.GetValueOrDefault<object>();
	return true;
	}
	break;
	case Argument argument:
	var argumentResult = bindingContext?.ParseResult.FindResultFor(argument);
	if (argumentResult is not null)
	{
	boundValue = argumentResult.GetValueOrDefault<object>();
	return true;
	}
	break;
	}

fixes #1917
fixes #1918

[am11]

@adamsitnik, do you have any recommendation what should be used here: https://github.com/dotnet/runtime/blob/f8bd9d29be973e0a9b82b87b9e50a0d3a77d1697/src/coreclr/tools/Common/CommandLineHelpers.cs#L187-L189? It (--make-repro) is a special facility where we create a repro package with command+arguments+artifacts (as zip). In there, we are checking if Option's value is default (set by default factory). Note this is not a hot path so using reflection is an option as a last resort. (to get by the compile error for now, I used reinterpretation style cast: (IValueDescriptor)(object)option 😅)

ps - I am in the middle of grand upgrade in runtime and jitutils repos. There is no rush, I'm gradually rebasing and picking up latest daily versions as I go further in my branch.

[am11]

dotnet/runtime#84229