Fix checking for the wrong metadata files for applications launched with a different program index (#7055)

* Fix checking for the wrong update metadata file

* Apply the same fix for dlc.json

* Use the base application ids for updates and DLCs in the GUI too

This shouldn't actually change anything, since the program index part of the application id
should always be 0 for all applications currently seen by the GUI.

This was just done for completeness.

src/Ryujinx.UI.Common/App/ApplicationData.cs

@@ -42,6 +42,8 @@ namespace Ryujinx.UI.App.Common
 
         [JsonIgnore] public ulong IdBase => Id & ~0x1FFFUL;
 
+        [JsonIgnore] public string IdBaseString => IdBase.ToString("x16");
+
         public static string GetBuildId(VirtualFileSystem virtualFileSystem, IntegrityCheckLevel checkLevel, string titleFilePath)
         {
             using FileStream file = new(titleFilePath, FileMode.Open, FileAccess.Read);