kernel/process: Make CodeSet a regular non-inherited object

These only exist to ferry data into a Process instance and end up going
out of scope quite early. Because of this, we can just make it a plain
struct for holding things and just std::move it into the relevant
function. There's no need to make this inherit from the kernel's Object
type.

src/core/hle/kernel/object.h

@@ -26,7 +26,6 @@ enum class HandleType : u32 {
     AddressArbiter,
     Timer,
     ResourceLimit,
-    CodeSet,
     ClientPort,
     ServerPort,
     ClientSession,