Log only successful syscalls by default, add command line option to log all syscalls

[krs85]

It can be very noisy (and arguably not useful) to track every syscall. It would be useful to be able to toggle between logging all syscalls and logging only ones that succeed. I'm going to add a command line option to opt into seeing all syscalls, and the default will be to only log calls that succeed.

• Add command line argument
• Add the logic to skip failed execve in the main event loop of execution.rs
• Handle this for open, openat, and creat.