Implement `SYS_process_vm_readv` and `SYS_process_vm_writev`

[doanbaotrung]

Feature: Implement SYS_process_vm_readv and SYS_process_vm_writev

1. Summary of Changes

• Mapped SYS_process_vm_readv (syscall 270) and SYS_process_vm_writev (syscall 271) in the guest system call dispatch table (dispatch.tbl and abi.h).
• Implemented sc_process_vm_readv and sc_process_vm_writev in the syscall translation layer (syscall.c).
• The system calls handle intra-process ("self") transfers by checking if the target process ID matches the caller's process ID.
• If target is self, it runs process_vm_copy_self(), which loops through the local and remote guest iovec vectors and copies data directly between the guest virtual memory addresses via safe guest read/write accessors.
• If the target process ID does not match the caller, it returns -ESRCH (No such process), as cross-process address space copies are not supported under the single guest runtime process model.

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2. Why it is Needed

• Self-Diagnostics and Memory Dumping: Many advanced user-space utilities (such as garbage collectors, custom memory managers, tracing/profiling agents, and crash-reporting runtimes) use process_vm_readv/process_vm_writev to safely inspect process memory regions or serialize memory state.
• Compatibility: When these diagnostics/tracing tools query self-memory and receive an ENOSYS (Function not implemented) error, they abort or disable critical crash-logging and monitoring capabilities.
• Safe Memory Transfer: Implementing intra-process copying via process_vm_copy_self allows guest applications to successfully query their own virtual memory layout using standard POSIX address-space APIs.