Handle scenario when record has less values than header

[Tolstovku]

Current implementation of EnumerateDynamicRecords() differs from that of original GetRecords() in case when record has less values than header. That is because only header length is considered in enumeration.

Example 1

CSV:

h1,h2,h3
v1,v2

GetRecords<dynamic>()

Using csvReader.GetRecords<dynamic>() as

    foreach(IDictionary<string, object> record in reader.GetRecords<dynamic>()) // EnumerateDynamicRecords() here for next example
    {
        foreach (var keyValuePair in record)
        {
            Console.WriteLine($"{keyValuePair.Key}: {keyValuePair.Value}");
        }
    }

Result:

h1: v1
h2: v2
h3:

EnumerateDynamicRecords()

Result:

h1: v1
h2: v2
h3: h3

Example 2

CSV:

h1,h2,h3,h4
v1,v2

GetRecords<dynamic>()

Result:

h1: v1
h2: v2
h3:
h4:

EnumerateDynamicRecords()

Result:

Unhandled exception. CsvHelper.ReaderException: An unexpected error occurred.
IReader state:
   ColumnCount: 2
   CurrentIndex: -1
   HeaderRecord:
["h1","h2","h3","h4"]
IParser state:
   ByteCount: 0
   CharCount: 17
   Row: 2
   RawRow: 2
   Count: 2
   RawRecord:
v1,v2

 ---> System.IndexOutOfRangeException: Index was outside the bounds of the array.
   at CsvHelper.CsvParser.GetField(Int32 index)
   at CsvHelper.CsvParser.get_Item(Int32 index)
   at CsvHelper.FastDynamic.CsvReaderExtensions.EnumerateDynamicRecords(CsvReader csvReader)+MoveNext() in ...\CsvReaderExtensions.cs:line 43
   --- End of inner exception stack trace ---
   at CsvHelper.FastDynamic.CsvReaderExtensions.EnumerateDynamicRecords(CsvReader csvReader)+MoveNext() in ...CsvReaderExtensions.cs:line 54