Add a share button to comments

[dullbananas]

Requirements

• This is a feature request and not a bug report. Otherwise, please create a new bug report instead.
• Please check to see if this request (or a similar one) already exists.
• It's a single feature. Please don't request multiple features in one issue.

Describe the feature you'd like

Comments, like posts, should have a button that shows the menu to share the comment's URL. It probably should have scrollToComments set to true.

In Safari, this would make it so much easier to share a comment URL, because the URL for only the post is used as the canonical URL, which is used for the share button shown by Safari.

[dessalines]

Would replacing one of those above work, probably the first one, the link? Seems excessive to have 3 share buttons.