Third Party Launcher (LeviLauncher) Support

**Is your feature request related to a problem? Please describe.**
for Third Party Launcher like [LeviLauncher](https://github.com/LiteLDev/LeviLauncher) and [mc-w10-version-launcher](https://github.com/MCMrARM/mc-w10-version-launcher), you cant add sideloaded instances using the "Find Installation" button. it will do nothing after your choose the instance.