main: Prevent installing base titles into NAND

Many users have been installing their base titles into NAND instead of adding them into the games list. This prevents users from installing any base titles and warns the user about the action.

src/yuzu/main.h

@@ -76,6 +76,7 @@ enum class InstallResult {
     Success,
     Overwrite,
     Failure,
+    BaseInstallAttempted,
 };
 
 enum class ReinitializeKeyBehavior {