Unable to reselect camera source after initial denied request

[peculiarPrince]

Once I had denied access to the camera, I was unable to re-access it at all.
Tried:

• reloading page,
• opening Opencast Studio in a new tab,
• opening it in an incognito tab, and
• manually allowing access by resetting site permissions on device and allowing Chrome access to the camera
• turning device off and on again
  
  

[peculiarPrince]

This bug only happened on the Android tablet: trying to reproduce it on an Android smartphone in Chrome did not reproduce the bug.

[lkiesow]

This should always happen if you deny access and select to remember your choice.
This may be happening in Android without checking that box, since Android doesn't easily fully closes an application.

Re-requesting permissions is not permitted by browsers.
But I've seen other applications display overlay hints explaining where to click.
We could add those for the most common browsers.