Prevent screen locking on timeout when web pages are open

[MaxZhaloba]

This issue should be fixed on all pages: main.html and vr.html

In theory, when there's a playing video on the page, browser prevents screen from locking. However we do have video streams on our pages, the screen locking still currently takes place in our case.

Course of action:

1. First of all, investigate how to prevent browser from screen locking using the video streams we have and why this currently does not happen. This is the recommended solution.
2. Only in case if we reasonably would not be able to use the first solution, we can use a third party library for this purpose.