Style updates to bookmark manager per @bradleyrichter

[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).

Fixes #4562
Fixes #2652

Auditors: @jkup @bbondy

Test Plan:

1. Launch bookmarks manager
2. Ensure it looks like the latest mockup here: Update styles for Bookmark Manager #4562
3. Try resizing the window
4. Enjoy 😄

[bsclifton]

Here's a screenshot showing the flexability of the folders area, which fixes #1187

It has a min-width of 220px and a flex-grow of 1 (versus the other having 5).
Adding more levels of folders will extend the size

How low can you go?

[bbondy]

@bradleyrichter could you review?

[srirambv]

@bsclifton The import button doesn't seem to be placed correctly compared to the one above, in the preview build

[srirambv]

Long folder names getting clipped

[bsclifton]

@srirambv those issues will be fixed with this PR 😄 This should also fix a failing test

[bradleyrichter]

Ideally we would have ellipses after a max width and a full-text on hover.

Later, drag-adjust column widths.

Please don't force the column width to fit the long folder names.

[bsclifton]

@bradleyrichter should there be a max width setting? Adding that would be fairly easy. Overflow can be handled with either ellipsis or by adding a horizontal scroll bar at the bottom

[bsclifton]

Screen caps of some of the changes we did:

New "All Folders"

shows when you do a search (otherwise hidden):

Demo of the new color highlights for sortableTable

cc: @darkdh
light gray = hover over item
medium gray = selected item
dark orange = hover over selected item

[jkup]

Looks great. A few tiny things:

1. The page has a scrollbar even with only 1 item.
2. Should we center the search bar on smaller devices?
3. Is it ok that the titles aren't scrollable on smaller devices? Not sure if it matters but it means you can't read the entire thing.

Pictures for 2 & 3

[bsclifton]

Sweet- thanks for the feedback, @jkup! I'll can work on a fix for 1 and 3 in a follow up 😄

@bradleyrichter what do you think about 2? (should the search box be centered if you reduce the window size- see @jkup's pic)

[bsclifton]

I'll go ahead and merge- @bradleyrichter I can address those items in a follow up (0.12.6, when adding folders). Please let me know!