c#: investigate if BitConverter is needed in cases where we receive a pointer

[jsturtevant]

Final nit, why we are doing the BitConverter.ToInt32 dance ?

this is coming from one of the other instructions that are generated via the wit-bindgen abi (https://github.com/bytecodealliance/wit-bindgen/blob/5d8fa6196b6382a90592c42aa63ad73f17760797/crates/csharp/src/function.rs#L400-L407)

Maybe we don't need BitConverter.ToInt32 in other cases? Maybe that something else to clean up (in a separate pr)

Originally posted by @jsturtevant in https://github.com/bytecodealliance/wit-bindgen/issues/1145#issuecomment-2643626588