Fix fullscreen only works for first video, iina#4202

This commit will:
- Remove a check in `PlayerCore.fileLoaded` that only put the player
  into full screen mode for the first file
- Remove the property `justLaunched` from `PlaybackInfo`

This causes the "Enter fullscreen" setting under the "When media is
opened" settings to when enabled put the player into full screen mode
for all videos, not just the first video played.

iina/PlaybackInfo.swift

@@ -91,7 +91,6 @@ class PlaybackInfo {
     }
   }
 
-  var justLaunched: Bool = true
   var justStartedFile: Bool = false
   var justOpenedFile: Bool = false
   var shouldAutoLoadFiles: Bool = false

iina/PlayerCore.swift

@@ -1381,12 +1381,8 @@ class PlayerCore: NSObject {
         miniPlayer.defaultAlbumArt.isHidden = self.info.vid != 0
       }
     }
-    // set initial properties for the first file
-    if info.justLaunched {
-      if Preference.bool(for: .fullScreenWhenOpen) && !mainWindow.fsState.isFullscreen && !isInMiniPlayer {
-        DispatchQueue.main.async(execute: self.mainWindow.toggleWindowFullScreen)
-      }
-      info.justLaunched = false
+    if Preference.bool(for: .fullScreenWhenOpen) && !mainWindow.fsState.isFullscreen && !isInMiniPlayer {
+      DispatchQueue.main.async(execute: self.mainWindow.toggleWindowFullScreen)
     }
     // add to history
     if let url = info.currentURL {