Prevent the app from quitting while the Fire button is active (#670)

Task/Issue URL: https://app.asana.com/0/1177771139624306/1202342287825730/f
Tech Design URL:
CC:

Description:

This PR cancels termination if the Fire button is burning data when quitting is attempted.

Author: samsymons

DuckDuckGo/App Delegate/AppDelegate.swift

@@ -128,9 +128,15 @@ final class AppDelegate: NSObject, NSApplicationDelegate {
             if alert.runModal() == .cancel {
                 return .terminateCancel
             }
+
             FileDownloadManager.shared.cancelAll(waitUntilDone: true)
             DownloadListCoordinator.shared.sync()
         }
+        
+        if FireCoordinator.fireViewModel.isBurning {
+            return .terminateLater
+        }
+
         stateRestorationManager?.applicationWillTerminate()
 
         return .terminateNow

DuckDuckGo/Fire/Model/Fire.swift

@@ -215,6 +215,7 @@ final class Fire {
                 completion?()
 
                 os_log("Fire finished", log: .fire)
+                NSApp.reply(toApplicationShouldTerminate: true)
             }
         }
     }
@@ -264,6 +265,7 @@ final class Fire {
                 completion?()
 
                 os_log("Fire finished", log: .fire)
+                NSApp.reply(toApplicationShouldTerminate: true)
             }
         }
     }

DuckDuckGo/Fire/ViewModel/FireViewModel.swift

@@ -25,6 +25,10 @@ final class FireViewModel {
 
     @Published var isAnimationPlaying = false
 
+    var isBurning: Bool {
+        fire.burningData != nil
+    }
+
     /// Publisher that emits true if burning animation or burning process is in progress
     var shouldPreventUserInteraction: AnyPublisher<Bool, Never> {
         Publishers