[ENHANCEMENT] Files doesn't recognize change in default app preferences in open windows

[iamkartiknayak]

Cosmic-files version:

cosmic-files:
  Installed: 0.1.0~1734538799~24.04~ee7954e

Issue/Bug description:
When changing the default app for a specific file type (e.g., video player from Cosmic Media Player to Clapper), an already open instance of Cosmic Files does not recognize the updated preferences. However, if a new instance of Cosmic Files is launched, it correctly identifies the updated preferences.

Steps to reproduce:

• Open Cosmic Files.
• Change the default app for a specific file type (e.g., videos) using Cosmic Settings.
• Try opening a file of that type in the currently open Cosmic Files window.
• Observe that it still uses the old default app.
• Open a new instance of Cosmic Files and attempt to open the same file type.

Expected behavior:
All open instances of Cosmic Files should dynamically recognize changes to default app preferences without requiring a restart.

Other notes: