CourseAnalytics: Data visualization for an offering

### Viewers
- [ ] A visualized chart (say a bar chart) that shows the top 10/20 students based on their total time spent on the course.
- [ ] A table of video viewers and their time spent on watching the videos of the offering

### Popular videos
- [ ] A visualized chart (say a bar chart) that shows the top 10/20 most popular videos (the popularity can be determined by its total watched time)
- [ ] A table of media and the # of users who watched the video and its total watched time

### Summary Table
- [ ] #150

> For the first 3 tables, the data structure is looks like this
```json
[
{
"user": {
"id" : "",
"email": ""
},
"medias": [
{
"mediaName": "",
"id": "",
"last1Hr": 12,
"last3Days": 12,
"lastWeek": 12,
"lastMonth": 12,
"total": 12
}
]
}
]
```

### Top search words
... More in the future

steps:
- create a redux store `course-analytics` in `src/redux/instructor/`
- I've set up the basics of the page for you in `screens/Instructor/CouseAnalytics`, you need to connect it to your redux store.
- Then take a look at the `MyCourses` or `Example`, and start to write your code.
- You can use https://classtranscribe-dev.ncsa.illinois.edu/instructor/ac5b1727-629c-443b-8c1a-cc1bd541af6a to find out how it looks like