Polyfil AgumentNullException.ThrowIfNull for .NET Frameowrk.

It should be possible in November 2026, when we drop support for .NET8/.NET9 and remove compilation on old SDKs.

while implementing, check all throw new ArgumentNullException calls.


https://github.com/SimonCropp/Polyfill/blob/df2446209164d1fc0207b8a9d6a4871db40dd64e/src/Polyfill/ArgumentExceptions/ArgumentNullExceptionPolyfill.cs#L12