Every fsinfo update re-draws the SidebarPanel

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There are two issues here:

• We re-render the SidebarPanel every time we get an inotify change event on the current directory, this is unneeded
• Every re-render runs cockpit.spawn and issues file --brief but when nothing is selected it runs /home/admin/undefined. Note that no console.warn is issued.

This is not a huge performance issue, but imo worth to fix.

[jelly]

The SidebarPanel get's all files passed to, so that explains the re-render on updates.