Enlarge click target for widgets in right sidebar areas

[lessbloat]

When widgets have been dragged to a sidebar, the only way to see the widget details is to click the tiny arrow on the right side of the widget.

Two out of the three users we tested had troubles figuring this out. See:

• 17:36 of ​this user test
• 8:50 of ​this user test

We should probably look at expanding the click area outside of the tiny little arrow on the right.

RE: 21247.diff

Expands the click area to the entire widget vs. just the arrow on the right. Prefixing .widget with #widgets-right limits this functionality to widgets in the right column.

We only need this on the header portion of the widget, not the body ;-)

Thinking that should be the same for all widgets, not just in the sidebars on the right. That would make the widgets consistent with the postboxes open/close. 21247-3.patch also removes use of .live() as it's deprecated.

In [21281]:

Widgets UI: make the whole "header" clickable to open/close the widget (same as postboxes), remove deprecated jQuery .live(), part props lessbloat, fixes #21247