This fixes an issue where closing stream search was not working if
user had not entered a search term and tried to close the search box
by clicking on the close icon; the problem was that we'd end up
re-opening the widget immediately after through event propagation.
Fixes: #11636.
We want the search widget, when visible, to be
outside the scroll container for the stream list.
One obvious use case is if you start scrolling, and
then realize it might be less effort to search.
Also, for user search, it already worked this way.
We have to add a couple resizing hooks here, but
it's not necessary to change the actual resize
calculation, since we move the section inside
of #streams_header, which is already accounted
for.
The only markup change here is to add
a `stream_search_section` class. I don't
know why we use `notdisplayed` here instead of
jQuery, or what `input-append` is for, but I
considered them outside the scope of this change.
We can also remove some crufty CSS that was
compensating for it being inside the container.
This run_test helper sets up a convention that allows
us to give really short tracebacks for errors, and
eventually we can have more control over running
individual tests. (The latter goal has some
complications, since we often intentionally leak
setup in tests.)