Allow changing client file cache path in Advanced Settings

[Xenius97]

Summary

Adds the ability to change the client-side file cache location from the Advanced Settings menu.
Two new buttons were introduced: Change, which allows the user to select a custom cache directory via a file explorer dialog, and Reset, which restores the default behavior.

By default, the client continues to use the cache path stored in the Windows Registry. If a custom cache path is defined in coreconfig.xml, it takes precedence. If the custom directory becomes unavailable or is deleted, the system automatically falls back to the default path.

Closes #4655

Motivation

Currently, the cache path is only displayed in the UI and cannot be modified from within the client.
Changing it requires manually editing the Windows Registry.

This change makes cache path configuration accessible from the UI while keeping backward compatibility and safe fallback behavior.

Test plan

1. Open Advanced Settings and click Change to select a custom cache folder.
2. Restart the client and verify that the new cache path is in use.
3. Click Reset, restart again, and verify that the default cache path is restored.

Checklist

• Code follows the coding guidelines.
• The pull request is small, focused, and easy to review.

[qaisjp]

Lets hash out the motivation and purpose on #4655 before proceeding on more implementation