On web, when a user highlights text with their cursor, we want to prevent 1) the text from being displayed to reveal the spoiler and 2) being copied prior to being revealed.
Linear: https://linear.app/comm/issue/ENG-2227/prevent-hidden-spoiler-content-from-being-revealed-by-textcursor
References:
https://caniuse.com/user-select-none
https://stackoverflow.com/questions/826782/how-to-disable-text-selection-highlighting
Depends on D5601