Do not ignore launchsettings.json for VS

Ignoring launchSettings.json does not make much sense. Now .NET CLI even considers this file when running with dotnet run, as you can read here.

This settings will be useful if shared among project members, so it should be commited to the repo.

Also, on the default .gitignore file generated by Visual Studio it is not ignored, so this causes confusion, as depending on how .gitignore was created it could be commited in or not.