Desktop: Open links in default browser and prevent popups

[timon-schelling]

Partly closes #2540.

Open links in default browser and prevents CEF from opening popups

logs before the second commit:

2025-08-05T18:11:29.118324Z ERROR graphite_desktop::cef::internal::browser_process_life_span_handler: Browser tried to open a popup at URL: https://graphite.rs/
2025-08-05T18:11:29.335806Z ERROR graphite_desktop::cef::internal::browser_process_life_span_handler: Browser tried to open a popup at URL: https://graphite.rs/
2025-08-05T18:11:48.109077Z ERROR graphite_desktop::cef::internal::browser_process_life_span_handler: Browser tried to open a popup at URL: https://graphite.rs/
2025-08-05T18:11:48.273723Z ERROR graphite_desktop::cef::internal::browser_process_life_span_handler: Browser tried to open a popup at URL: https://graphite.rs/