settings: Add org.gnome.desktop.interface namespace with glob support

[FreddyFunk]

xdg-desktop-portal-cosmic settings portal didn't provide org.gnome.desktop.interface settings and didn't support glob patterns in ReadAll. GTK3 queries ReadAll(["org.gnome.*"]) at startup. Therefore the glob never matched, so text-scaling-factor was never delivered, leaving gtk-xft-dpi at 0. WebKitGTK uses that for viewport math, causing ~1,000,000x inflation, causing broken UIs in some apps, like the Hytale Launcher in the linked issue below.

closes pop-os/cosmic-epoch#3062

2026-03-09.20-10-11.mp4

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