Support fixed-size arrays in `Struct`

[mrexodia]

This can currently not be ported:

def _RTL_PROCESS_MODULE_INFORMATION(arch: Architecture):
    class _RTL_PROCESS_MODULE_INFORMATION(ctypes.Structure):
        _alignment_ = arch.alignment()
        _fields_ = [
            ("Section", arch.ptr_type()),
            ("MappedBase", arch.ptr_type()),
            ("ImageBase", arch.ptr_type()),
            ("ImageSize", ctypes.c_uint32),
            ("Flags", ctypes.c_uint32),
            ("LoadOrderIndex", ctypes.c_uint16),
            ("InitOrderIndex", ctypes.c_uint16),
            ("LoadCount", ctypes.c_uint16),
            ("OffsetToFileName", ctypes.c_uint16),
            ("FullPathName", ctypes.c_ubyte * 256),
        ]
    return _RTL_PROCESS_MODULE_INFORMATION()