Fix broken left sidebar navigation
Sidebar navigation is broken and it's introduced in !6627 (merged). Sidebar pin and hamburger icons were a tag before with # link on them. That was the main reason why page jumps to top. !6627 (merged) was trying to prevent default action but it interferes with the navigation links. I don't want to tweak event listeners for sidebar, instead I just replaced a elements with div because I think there is no point to have them as a.
PS: This MR basically reverts !6627 (merged). I don't want to add another revert commit instead I reverted it in my editor and committed.