Read null terminated UTF32 string

[badcel]

Currently several UTF32 strings are read from the hid api. To do so the length of the string must be calculated which is done manually in UTF32 class.

Verify if there is a method inside dotnet which can do this automatically. For comparison there is MemoryMarshal.CreateReadOnlySpanFromNullTerminated for UTF8 available.

The same is needed for Unicode (16 bit wide encodings).