Allow a per-registration configurationAction on service and actor registrations #70

Follow-up to #57, which is closed now that the global hook it asked for has shipped.

RegisterServiceFabricSupport accepts a configurationAction that runs while each service or actor lifetime scope is being built. It's the only place a component that needs ServiceContext at construction time can be registered, and it works — but it's global: the same action runs for every service and actor in the host.

That's awkward when registrations differ per service. The original issue ran into it directly: registering IReliableStateManager only makes sense for a stateful service, so with a single global action you end up branching inside the callback on what kind of service is being constructed.

Proposal

Accept an optional Action<ContainerBuilder> on the individual registration methods, running after the global action:

builder.RegisterStatefulService<MyService>(
    "MyServiceType",
    configurationAction: b => b.Register(c => /* stateful-only registrations */));

Applies to RegisterStatelessService, RegisterStatefulService, and RegisterActor. The plumbing already exists — IStatelessServiceFactoryRegistration and friends thread a configurationAction through to BeginLifetimeScope, so this is mostly a matter of composing a second action alongside the global one.

The global hook stays as-is, so this is additive for callers who don't need per-service registrations.