Re-introduce bookmark modal

[bsclifton]

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).

Re-introduce bookmark modal

• add/edit current site uses the bookmark hanger
• all other cases use a new control which wraps a modal around a slightly different
  version of the bookmark hanger.

Fixes #5103

Auditors: @jkup, @bbondy

[bsclifton]

This might need some small tweaks (ex: it should auto-focus on text field when opened, etc) but it's working good 😄 Ready for review

[bsclifton]

Has a positioning issue (too far right horizontally and not centered vertically) and (if time allows) would be nice to match modal closer to mockup in #2894 (comment) (including adding a close button)

new bookmark folder

create new bookmark

add bookmark (with the hanger)

[jkup]

Moving the code into a separate file LGTM! I think we need the modal centered and the input auto-focused before we ship but looking great so far!

[bsclifton]

@jkup @bbondy updated PR- I fixed the centering of the modal and then added a close button in the top right

Close button does not show for the bookhanger mode

Ready for re-review / merge

[jkup]

@bsclifton looking great! I think it's ready to ship, just one question for @bradleyrichter:

When a bookmark from the bookmarks bar is right clicked on and you click edit, should it be the centered no arrow or the arrow pointing at the star? I know the final design wants the arrow to point to the bookmark but I mean for now..

Other than that ready to ship!

[bbondy]

merging!

[luixxiul]

@bbondy Was this included in 0.12.7 Preview1?

[bbondy]

no

[bsclifton]

Created #5163 for the remaining style work. @bradleyrichter if you get a chance, can you pls check it out, add notes, and prioritize? thanks 😄