[Refactor] Add system-related syscalls to threei with corresponding type conversions in typemap

[Yaxuan-w]

This PR adds system-related syscalls to threei, along with the corresponding type conversion functions in typemap lib.

Additionally, I noticed that getrlimit and setrlimit currently only have impl definitions in the main branch, but there are no corresponding entries in the dispatcher.rs. I also have not found any references where these functions are invoked. It is therefore unclear whether we should fully implement and expose them at this point.