support workload(command) tracing

Example for syscall tracing:

ktap -T scripts/syscalls.kp -c $cmd

Looking all kernel function execued when running your command:

ktap -e 'trace "ftrace:function" function (e) {print(e)}' -c $cmd

Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@gmail.com>