[Breaking Change] Update RequiredIf Validator to Accept UDF/Closure and Update UDF Validator for Consistency When Handling Null/Empty Values

[homestar9]

This change adds additional functionality to the RequiredIf validator. Now, you can pass a UDF/closure to the validator to dynamically evaluate whether the field is required or not. The UDF/closure should return true if the field is required and false if not.

Example:

myField = {
 // myField is required if today is Monday.
 requiredIf = function( value, target, errorMetadata ) {
        return dayOfWeekAsString( dayOfWeek( now() ) ) == "Monday";
 }
}

The UDF validator was also updated for consistency (see ortus-docs/cbvalidation-docs#13) and will treat null/empty values as valid. Developers who want to dynamically determine whether a field should be required will need to switch to using RequiredIf. This is a BREAKING change and should be reserved for the next major version of CBValidation.

[homestar9]

This would be better if broken up into two pull requests. Closing.