change hover behavior to make modules looks both draggable and clickable
add tooltip to further indicate simultaneos drag/click behavior

This is problematic because it 1) will interfere with showing full title
and 2) it also appears in picker, not just TOC.
instead of entire item feeling draggable, make it appear based on a hook at left

includes several styling changes to make the drag hook/handle look nicer
with the other icons/text
Tom hooked me up with an isPicker variable: sweet (like :cake:)
Tom made me an ancestorSelected variable so we can have context-based messaging. Thanks :cake:
prevent drag handle from showing up in picker books
Merge branch 'refs/heads/58359238-make-reordering-discoverable' into testing
add "Drag to add a new" instructions for the semantic elements
Merge branch 'refs/heads/58371606-semantic-drag-instructions' into testing
Merge branch 'testing' of github.com:oerpub/github-book into testing