[Bug] `Reset to default` does not appear after importing a theme (needs refresh)

[iamkartiknayak]

Issue/Description:
In COSMIC Settings → Appearance, after importing a theme after resetting to default, the Reset to default option does not appear immediately.

For the option to show up, it is necessary to navigate to a different settings page and then return to Appearance, which effectively refreshes the view.

Version:
cosmic-settings:
Installed: 1.0.2176910375524.04~1839ad3

Steps to Reproduce:

• Open COSMIC Settings
• Go to Appearance
• Reset the theme to default
• Import a theme
• Observe that Reset to default is not shown
• Navigate to another settings page or parent page
• Return to Appearance

Expected Behavior:
Reset to default should appear immediately after a theme is imported, without requiring navigation away and back.