I made the header sections above all our settings
panel lists more consistent.
Before this change:
* some lists had titles, others didn't
* the placement of the filter box was random
* alerts strangely went between the filter box
and the list
* filter boxes were too large
* CSS was haphazard
* forms were squished against tables
Now all the settings with list have consistent
HTML, CSS, and look-and-feel in the area directly above
their list of items.
With the exception of Custom Profile Fields, all the
lists with headers above them happen to be based on
ListWidget, but the header styling is not coupled
to ListWidget, because we want consistent headers
even if Custom Profile Fields has a non-ListWidget
list (due to its drag&drop features).
This commit removes the unnecessary `data-list-widget` attribute
present in the <div> and <tbody> tag for muted_topics and muted_users table.
It became unnecessary/useless in 19cf6d0e04 and
then was renamed while still useless.
Also uses the correct variable name `muted_topic` and `muted_user`
instead of `muted_topics` and `muted_users` to render a item of their list
in DOM through Listwidget.