When an issue is not found, display a message that explains what's going on

Right now if I go to a URL of a missing issue (possibly deleted earlier), all I can see is a blank screen:


Only if I open up the console, I can see that Huly couldn’t find the issue.

Instead of displaying a blank screen, display a clear message that tells what happened and offers a workaround, such as opening the list of issues in the current project. Here’s an example:

>
> 404 (:
> We couldn’t find this issue.
>
> The issue could have been deleted, or you don’t have sufficient permissions to view it.
>
> Would you like to [see all issues in this project](insert a link to all issues in the containing project)?

_{View in Huly UBERF-5435}