add support for mobile touch events

Trying to listen to touchstart and touchend events and prevent the browser built-in contextmenu by preventDefault() in touchstart, which then requires manual dispatch of click events for profile popups in pleroma-fe.

However, it seems that one cannot scroll the page normally when the touch starts on the avatar, and I was not able to find a way to fix this.

Please pardon me if there are any amateur mistakes. Thank you!