Change upload progress tracker

[nikeee]

We use a library that was compiled for .NET Framework v4.6.1 for tracking the upload progress. However, we get a warning using this.

10>F:\Projects\HolzShots\src\HolzShots\HolzShots.csproj : warning NU1701: Package 'System.Net.Http.Formatting.Extension 5.2.3' was restored using '.NETFramework,Version=v4.6.1, .NETFramework,Version=v4.6.2, .NETFramework,Version=v4.7, .NETFramework,Version=v4.7.1, .NETFramework,Version=v4.7.2, .NETFramework,Version=v4.8' instead of the project target framework 'net6.0-windows7.0'. This package may not be fully compatible with your project.

We only use one class of that assembly: System.Net.Http.Handlers.ProgressMessageHandler
Turns out, that there is much more to it than just copying that class from somewhere.
As this class intended for Pre-.NET-Core ages, there must be anequivalent for .NET Core and up. We should find it to resolve this warning.

[nikeee]

#94 would probably require us to support multiple stages in the upload (a stage is a request), since hurl allows an indefinite number of requests.