Localization language change clears QueryString

[zvasilius]

I use some query params for user registration or other purposes:
http://localhost:5000/Controller/Action?queryParam=value

After user changed localization language to different, SelectLanguage.cshtml posts
var returnUrl = string.IsNullOrEmpty(Context.Request.Path) ? "/" : $"{Context.Request.Path.Value}";
back, page will be re-rendered, but without query params:
http://localhost:5000/Controller/Action

Can be easy fixed by changing SelectLanguage.cshtml to this one:
var returnUrl = string.IsNullOrEmpty(Context.Request.Path) ? "/" : $"{Context.Request.Path.Value}{Context.Request.QueryString}";

I can create PR with fix, just not sure if it's good idea.

[skoruba]

@zvasilius - thank you for reporting this issue, for sure, please you can make a PR. 👍