This moves some code from settings_display.js
into the new module settings_config.js.
Extracting this module breaks some dependencies
on settings_display.js (which has some annoying
transitive dependencies, including jQuery).
In particular this isolates stream_data from
from settings_display.js.
Two of the three structures that we moved here
weren't even directly used by settings_display.js,
since we do a lot of rendering in the modules
admin.js and setting.js.
We make get_all_display_settings() a function
to avoid a require-time dependency on page_params.
Breaking the dependencies simplifies a few
node tests.
Most of the node test complexity came from the
following commit in March 2019:
5a130097bf
The commit itself seems harmless enough, but
dependencies can have a somewhat "viral" nature,
where making stream_data depend on settings_display
caused us to modify four different node tests.