Redesign user tracker into user statistics

Describe the bug

User tracker not displaying anything

To Reproduce

1. Open User tracker as admin

Screenshots

Output in Web Console

window.controllers/Controllers is deprecated. Do not use it for UA detection. index.js:1362
Cookie “XSRF-TOKEN” has been rejected because it is already expired. info
Some cookies are misusing the recommended “SameSite“ attribute 2
Cookie “cookietest” will be soon rejected because it has the “SameSite” attribute set to “None” or an invalid value, without the “secure” attribute. To know more about the “SameSite“ attribute, read https://developer.mozilla.org/docs/Web/HTTP/Headers/Set-Cookie/SameSite fp.esm.js:292:21
Cookie “cookietest” will be soon rejected because it has the “SameSite” attribute set to “None” or an invalid value, without the “secure” attribute. To know more about the “SameSite“ attribute, read https://developer.mozilla.org/docs/Web/HTTP/Headers/Set-Cookie/SameSite fp.esm.js:296:30
Cookie “XSRF-TOKEN” has been rejected because it is already expired. account
Cookie “XSRF-TOKEN” has been rejected because it is already expired. 4 time
Cookie “XSRF-TOKEN” has been rejected because it is already expired. notifications
Cookie “XSRF-TOKEN” has been rejected because it is already expired. time
Cookie “XSRF-TOKEN” has been rejected because it is already expired.

[1-alex98]

This is already in the newest version as far as I am aware.

[krusche]

I just had an idea. Instead of removing this page, we should rename it and show the following interesting activities / metrics:

1. How many unique users have logged in to Artemis in the last X days 2a) How many unique users have participated in an exercise (i.e. have a submission with a submission) in the last X days 2b) How many total submissions (submission date) have been made in the last X days
2. How many results (with how much feedback) have been created (completion date) in the last X days
3. How many unique tutors have corrects an assessment (i.e. there is a manual result with completion date) in the last X days
4. How many exercises have been released in the last X days
5. How many exercises have been due in the last X days
6. How many exams have been conducted, how many individual student exams have participated (based on submissionDate) in the last X days

X should be a variable that can be specified on the page, e.g. 3, 7, 30, 90, 180, 365

There are probably more statistics that might be interesting.