Added support for collections of simple types (i.e. List<string>)

[psampaio]

This follows @matthetherington 's implementation of PR #205 (for #204).

If you have a this model/validator:

public class PersonModel
{
    public required string Name { get; set; }
    public required List<string> AddressLines { get; init; }
}

public class PersonModelValidator : AbstractValidator<PersonModel>
{
    public PersonModelValidator()
    {
        RuleFor(m => m.Name)
            .NotEmpty()
            .WithMessage("Name is required.");

        RuleForEach(m => m.AddressLines)
            .NotEmpty()
            .WithMessage("Address {CollectionIndex} is required.");
    }
}

field validation is not working. Validation summary shows the errors, but you cannot link them to validation messages.

Here's what I believe is happening:

• ValidateField is called, but the FieldIdentifier gives the property path as AddressLines.0
• There's a mismatch with the validationResult.PropertyName, which is calculated as AddressLines[0] (same as the name tag if you use editContext.ShouldUseFieldIdentifiers = true).
• .Where(validationFailure => validationFailure.PropertyName == propertyPath) fails

Assuming this analysis is correct, you can either 1. change the PropertyPath to have the AddressLines[0] format or 2. change the validationResult.PropertyName to have the AddressLines.0 format. 1 is happening somewhere inside ValidateAsync, but I couldn't figure out where, so I went with 2.

What I changed:

• Handle the simple type collections in ToFieldIdentifier in case there are no more tokens and the remaining property path ends with "]"
• Use that method to convert validationResult.PropertyName to the correct format and back to a property path.

I've done some testing, but I it's likely I'm missing some use cases.

[pwelter34]

Could you provide more of a sample to reproduce issue? Looking for the razor side of the code. thanks