The commit fixes the issue in which the settings sidebar would
overflow into the settings header when scrolled; it also adds
border-box model to minimize calculations and magic numbers.
This commit adds a new module settings_defaults.js which calls
the functions in settings_display passing appropriate container
element and settings object as parameters.
We also add one more parameter for_realm_settings to some of the
functions in settings_dislay to differentiate between the user
and realm-level settings.
Anders Kaseorg
sayamsamal
Ganesh Pawar
Morgan Njaw
Sahil Batra
Jonny Tran
sahil839