Error while using Model.Save()

**System Information (please complete the following information):**
- Checked on multiple systems (win 10, win 2019,2021 server)
- ML.NET Version: ML.NET 1.7.0

- .NET Core 2.2.3

**Describe the bug**
When saving trained model of very large size, xx GB the exception is thrown with the inner exception "The length cannot be greater than the capacity. ParameterName valueCount at System.Text.StringBuilder.Append() at Microsoft.Ml.Data.ReadOnlyMemoryUtils.AppendSpan ...etc
What I think is that the Save() uses StringBuilder.Append(char*,Int32) method and the int32 is a problem.

**To Reproduce**
1.Train extra large model
2.Try to save it with Model.Save()