Changes to both the Client and Server projects

Client Changes

The following changes were made to the sample Client application:

Added HealthChecks (including Uptime & OpenIdConnect integrations).
Added new configuration section to hold license information (includes the options class LicenseOptions)
Added Duende BFF package to allow server-side initiated logouts to be communicated to the client.
Added new endpoints in HomeController.cs to handle Remote Error, Access Denied and Logged Out events.
Extended the ParOidcEvents class to include handling Remote Error, Access Denied and Logged Out events.
Minor update to the _Layout.cshtml view to indicate whether a user is currently authenticated or not.
Swapped out magic strings in the Startup.cs for appropriate constants.
Ensured that client secret for PAR is loaded from IOptions<IdentityProviderOptions> and not a hardcoded string.

The following changes were made to the sample Identity Server:

InitializeDatabase(...) changed to extension method and given option to run or not run the seeding steps.
DI registration for ConnectionStrings was redundant and so removed.
Local instances of ConnectionStrings and ApplicationKeys created using new GetCustomOptionsConfiguration extension method.
Updated version of HealthChecks.Uptime to latest for .NET 8.
Switched the default values for ShowLogoutPrompt and AutomaticRedirectAfterSignOut
Removed the guard clauses specific to .NET 6 & 7 in program.cs as the project is now fully targeting .NET 8