Add estimated time function

On the weekend, I refactored the front-end plan to append the code, and divided all the elements in each plan to deal with it. After that, the code looks much cleaner. Then the estimated time function is added. When adding a plan, you can optionally fill in the estimated completion time. If the estimated completion time is filled in, the plan is in the suspended state by default. The user can start the plan at any time, and the system starts to accumulate the time used. Of course, the user also You can temporarily schedule at any time, and the system will also pause timing until the next time the user starts scheduling. In addition, users can see the reminder that the plan is close to the estimated time and exceeding the estimated time, and can see the time spent by the plan when the plan is in the pending state.