Simplify conditional package references in all projects
Remove the custom PRIVATE_BIN define, use the built-in NETFRAMEWORK instead
Also use the Visual Studio 2022 image on AppVeyor because VS 2022 is required for the .NET 6 SDK
Add a reference to Microsoft.TestPlatform.ObjectModel so that dotnet test also works on Linux and macOS for the .NET Framework targets
Depend on Microsoft.Extensions.Configuration.Binder: there's no need to depend on Microsoft.Extensions.Options.ConfigurationExtensions, taking a dependency on Microsoft.Extensions.Configuration.Binder is enough for what Serilog.Settings.Configuration needs to do.
PRIVATE_BINdefine, use the built-inNETFRAMEWORKinsteadMicrosoft.TestPlatform.ObjectModelso thatdotnet testalso works on Linux and macOS for the .NET Framework targets