feat(word-counter): added word counter
- In the bottom right corner, we'll create a new Toolbar that eventually will include the counters info, shortcuts modal, and help.
- When the user has no text selected the counter should reflect the total words of the chapter.
- On text selection it should show the current selection counter. As the note's content is inline and saved in the annotation when a note is selected its text should be included in the count.
- Clicking the counter, should display the popover that exists in the design, with info for some additional counters. For now, tables, images, footnotes, and block-level nodes (paragraphs, titles, extracts, etc -- as one counter) should be enough. No need to bother with spelling mistakes or last saved for now.