Application logout doesn't support automatic redirect post signout, which Duende added a while back

[omon77]

Describe the bug

When application logs out, the application stays on STS's logged out page.
Duende added support for redirecting the application to the configured/specified url a while back.

Looks like missed merges start with this options class:
https://github.com/DuendeSoftware/IdentityServer/blob/e9860c6488f90e8fbc11a4452b9dd111dbfae933/hosts/main/Pages/Account/Logout/LogoutOptions.cs

Sample code:
https://github.com/DuendeSoftware/Samples/blob/main/IdentityServer/v7/SessionManagement/IdentityServerHost/Pages/Account/Logout/LogoutOptions.cs
And Logout action methods:
https://github.com/DuendeSoftware/Samples/blob/main/IdentityServer/v7/SessionManagement/IdentityServerHost/Pages/Account/Logout/Index.cshtml.cs

[skoruba]

I will check it, can you send a PR with some improvements?
Thanks!

[omon77]

@skoruba , I can give it a shot...

[skoruba]

@omon77 - would be great! thanks.