When the user sees no results in their admin sidebar query,
we are adding two additional links:
* "Search site settings" - Navigates to the site settings page
with the filter prefilled in the search
* "Admin user list" - Navigates to the user list with the filter
prefilled in the username search
This will bridge the gap until we have a full admin-wide search.
Also make admin site setting search param refresh on filter changes
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Co-authored-by: Jarek Radosz <jradosz@gmail.com>
With the new admin sidebar restructure, we have a link to "Installed plugins". We would like to ensure that when the admin is searching for a plugin name like "akismet" or "automation" this link will be visible. Also when entering the plugins page, related plugins should be highlighted.
Before, the `back to forum` link was part of experimental admin navigation. It means that the link could be filtered out.
Because it is essential navigation, it should not be part of sidebar links and should be moved above the filter.
We have separated and combined modes for sidebar panels.
Separated means the panels show only their own sections,
combined means sections from all panels are shown.
The admin sidebar only shows its own panels, so it must set
the mode to separated; however when we navigate to chat or
home we must revert to the initial mode setttings.
