A logger for Teaclave services. It can collect logs to a buffer. Logs not saved to buffer can be logged by another logger that implements log trait.
When the logger is imported in the execution service, it can send the logs during a task to a buffer. The kv_unstable feature in the log crate is used to pass the pointer to the buffer to the logger. After the buffer is set, the logger will save logs to the buffer. The logger will drop the task logger after receiving a null pointer. Another logger which we call secondary logger will handle the logs coming afterwards if it is set. The logs before the task starts are sent to the secondary logger as well.