Tweak ContentSafetyOptions.Enabled attribution and stream-line ServiceExtensiosn

[crickman]

Motivation and Context

Unhandled exception. Microsoft.Extensions.Options.OptionsValidationException: DataAnnotation validation failed for 'ContentSafetyOptions' members: '' with the error: ''Enabled' must be a string.'.
   at Microsoft.Extensions.Options.OptionsFactory`1.Create(String name)
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
   at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
   at System.Lazy`1.CreateValue()
   at Microsoft.Extensions.Options.OptionsCache`1.GetOrAdd[TArg](String name, Func`3 createOptions, TArg factoryArgument)
   at Microsoft.Extensions.Options.OptionsMonitor`1.Get(String name)
   at Microsoft.Extensions.DependencyInjection.OptionsBuilderExtensions.<>c__DisplayClass0_1`1.<ValidateOnStart>b__1()
   at Microsoft.Extensions.DependencyInjection.ValidationHostedService.StartAsync(CancellationToken cancellationToken)
--- End of stack trace from previous location ---
   at Microsoft.Extensions.DependencyInjection.ValidationHostedService.StartAsync(CancellationToken cancellationToken)
   at Microsoft.Extensions.Hosting.Internal.Host.StartAsync(CancellationToken cancellationToken)
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost host, CancellationToken token)
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost host, CancellationToken token)
   at CopilotChat.WebApi.Program.Main(String[] args) in C:\Users\crickman\source\repos\sk-chat-copilot\webapi\Program.cs:line 115
   at CopilotChat.WebApi.Program.<Main>(String[] args)

Description

• I think the whitespace instruction confused the validation on the type.
• Reducing repeated code / increase consistency in ServiceExtensions.cs

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄