Improve the UI of Comments: Comment look

Proposal link: https://design.xwiki.org/xwiki/bin/view/Proposal/CommentsAnnotations#HProposal235:Commentslook

Improvements:
#1 We add the "View thread" button that collapses or expands the sub-comments of a comment. On collpase, the chevron is pointing to the right, on expand, it is pointing downwards.
#1.1. Ideally, if not too hard to add, this "View thread" button also has the number of sub-comments of the initial comment. If there are 0 sub-comments, the "view thread" button isn't viewable.
#2 Quotes get a new look, with a big quote at the beginning, followed by big italic link-colored text.
#3 Comment actions get added below the comment content, with labels.
#4 Annotations should have their look updated to be cohesive with comments.