Highlighting comments

**Is your feature request related to a usage problem(not a bug?)**
In YT when u go to the comment section and click on the comment time stamp (timestamp is next to the username in FreeTube) for example 1 Day ago then the comment gets highlighted and get pinned to the top of the comment section even when u close the vid and come back later to rewatch.
This would be handy because if u want to rewatch the video the valuable information is still pinned at the top.

**Describe the solution you'd like to see implemented**
Click on the timestamp to highlight and dehighlight a comment.
Highlighted comments have priority over pinned ones by the channel owner.

**Describe alternatives you've considered**
None.

**Screenshots**

https://user-images.githubusercontent.com/73130443/104846583-2c545480-58d3-11eb-9b8e-190066656958.mp4

**Additional context**
None.