Improve the UI of Comments: Annotation look

Proposal link: https://design.xwiki.org/xwiki/bin/view/Proposal/CommentsAnnotations#HProposal234:Annotationlook

Improvements
#1 The profile picture is much smaller, focusing the attention on the text.
#2 We keep the date & time on the same line with the name of the user.
#3 We add a "x" icon to close the annotation in a easier way. Currently, the user has to click the annotation icon to close the annotation.
#4 We add a "Mark as solved" button that when clicked turns an annotation into a simple comment.

Looks: