feat(bookmark): New bookmark actions

• "Add/Remove Bookmark" buttons in annotation popup context menu,

  which share the annotation's viewport and use annotation's content as the title.

• "Expand/Collapse all" buttons in bookmark list context menu, TOC-like.

See also !1262 (closed).

@teams/vdg

1. More than once I found an annotation in one lecture note or some paper has the importance beyond the document itself, in which case I had to manually add a bookmark for it. The Add/Remove Bookmark buttons in annotation context menu can simplify the process.
2. This need emerges naturally when I search for "Gauss" in my bookmark list, the folder items are collapsed by default and I can't see if the matched bookmark items are "Gauss lemma" or "Gauss theorem" or even "Gauss curvature" etc, after all, it is a small change.

Important

The small "Add Bookmark" button in annotation popup menu is a lifesaver for me, as I often browse many textbooks, lecture notes, and papers. When I want to recall certain concepts I have annotated, I have to rely on searching my bookmark list to find them because open each of relevant textbooks to search for the annotation is tedious, not to say I often forget the exact name of the paper or the lecture note number.