feat: add requirement for denying guest users

[h3rmanj]

As a developer, I expect to be able to easily allow all members of a tenant to access my application, without needing to set up roles and manual assignment.

However, Azure AD allows for guest users, that applications like Teams rely on. These guest users will then by default have access to applications that doesn't have any roles, but still only should be accessible by tenant members.

This PR introduces the DenyGuests extension to AuthorizationPolicyBuilder, which easily lets the developer deny guests users access to their applications with policies.

I think that many enterprise application would want this behavior by default, and without it, the application would be exposed to some vulnerabilities.

//cc @loekensgard @JonasKs

[h3rmanj]

Not locked on the naming of this. I see many requirements are prefixed with Require, but RequireTenantMembers or RequireNonGuests sounds weird and isn't as explicit in what it tries to achieve.

[loekensgard]

@microsoft-github-policy-service agree

[jmprieur]

thanks @h3rmanj
Adding more authorization is definitively something we want to do, but we are thinking of doing it a bit differently
cc: @GeoK

[h3rmanj]

Mind sharing your thoughts? This is how we've done it internally for now, but we'd love to hear the plans for actual implementation in the SDK or even Azure itself.