Student Notes UI

This work is for [TNL-932] (https://openedx.atlassian.net/browse/TNL-932)

@polesye Ping me with any questions, please.

CC'ing @talbs @explorerleslie 
I was thinking if someone made a highlight in the middle of a sentence we may want to use ellipses to suggest it's a snippet from the middle of a line. However, if that's not how the tool works, then we can forego the prefix ellipsis.

The "more" link is used to clip (via JavaScript) notes to something manageable in case someone clips a very long note. There should be a "more" link, and then a "show less" link.