Mono incorrectly handles nuint to floating-point conversions

[tannergooding]

#69756 has several failures that occur across Mono:

Assert.Equal(unchecked((nuint)0xFFFF_FFFF_FFFF_F800), NumberBaseHelper<nuint>.CreateChecked<double>(+18446744073709549568.0));

Assert.Equal(unchecked((nuint)0xFFFF_FF00_0000_0000), NumberBaseHelper<nuint>.CreateChecked<float>(+18446742974197923840.0f));

In both cases the double and float used is the smallest representable double that is less than ulong.MaxValue and therefore it should always succeed.

However, Mono incorrectly throws System.OverflowException instead. The same tests exist for ulong where things are passing as expected.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[SamMonoRT]

@BrzVlad - similar to other issue, please investigate.