Improved dnd for bookmarks manager (dnd refactor)

[NejcZdovc]

• 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).

Resolves #6246

Part of this PR is also a refactoring, so that we can use dnd in other components.

@bsclifton Can you please check out my first commit Removed dnd in url bar. In 5837fc5 you added dnd for URLIcon. I don't see why this should be here (couldn't find anything about it in parent issue). Is it ok to remove it? If you dnd search icon in the current release you get error like this:

[bbondy]

all browsers allow you to drag that to bookmarks bar to create a bookmark, I don't think removing it is something we should do.

[NejcZdovc]

@bbondy I am talking about URL bar, not bookmarks bar. This code:

browser-laptop/app/renderer/components/urlBarIcon.js

Lines 103 to 104 in af368d3

	onDragStart={this.onDragStart}
	draggable

.

Try dnd search icon and you will see an error.

[bbondy]

Yes I'm talking about the same, but you can take the space to the left of the URL and drag to the bookmarks bar to create a new bookmark from the site you're on.

[bsclifton]

like @bbondy said, it's expected to be able to drag that are (which works great for me in master and our latest release too). That is actually how I store all of my bookmarks 😄

@NejcZdovc the error (as shown in your screenshot) appears to a regular mutable JavaScript object when this control is expecting an Immutable.js object

[NejcZdovc]

@bbondy @bsclifton If I am honest I was not aware this was possible. I am always creating bookmarks from tabs. I tried it and it's working, so yes we need to leave it as it is, only fix this error.

[bbondy]

ya I always create my bookmarks using it too, previously browsers used to put a site's favicon in the urlbar, but that led to sites using lock icons as their favicon which is a security problem, so browsers stopped displaying the lock there, but still allow dragging from that spot.

[bbondy]

just a heads up that DND is going through some changes due to tab tear off work.

[NejcZdovc]

Yeah I saw your PR and that's why I put a breaks on this PR and split sites PR.

[bsclifton]

Closing this PR for the moment, since it's blocked. Please do reopen when you have time to revisit 😄 Thanks!