Document Service Fabric interception, scoping, and package versioning

[tillig]

Fixes #187.

Three long-standing issues on the Autofac.ServiceFabric repo turned out to be documentation gaps rather than code defects. They're being closed in favor of #187, and this covers them.

What's added

Registration Requirements — the page never mentioned that every registered service and actor type is wrapped in a dynamic proxy, or what that requires (class, not sealed/abstract, only virtual members intercepted). Those constraints only existed in API XML docs.

Internal Service Types — resolves Autofac.ServiceFabric#49. An internal service type needs InternalsVisibleTo for DynamicProxyGenAssembly2, and which form depends on whether the consumer's own assembly is strong named, because Castle only signs its generated assembly when the assembly holding the proxied type is signed. Using the keyed Castle.Core.Internal constant from an unsigned assembly is what produces Access is denied — a genuinely misleading error for the actual cause. Added a note saying so explicitly, since people reasonably assume it's about whether Autofac.ServiceFabric is signed.

Service and Actor Lifetime Scopes — resolves Autofac.ServiceFabric#51. Documents that the SF context objects are registered into the per-replica child scope, not the root container, and therefore that a component depending on ServiceContext can't be SingleInstance(). Shows the failing registration next to the InstancePerMatchingLifetimeScope("ServiceFabric") fix. Also notes that Lazy<T>/Func<T> don't help, since that's what the reporter tried first.

Adding Registrations to the Service Scope — documents the configurationAction parameter of RegisterServiceFabricSupport, which shipped in v4.0.0 and was never documented. Uses the Application Insights FabricTelemetryInitializer example from Autofac.ServiceFabric#57, which is the scenario it was built for.

Service Fabric Package Versions — resolves Autofac.ServiceFabric#18, open since 2017. The Microsoft.ServiceFabric.* packages pin each other to exact versions, so the version Autofac.ServiceFabric depends on effectively sets the SF package version for the whole consuming project. Mixing versions yields NU1608. Documented as guidance because it's inherent to Microsoft's versioning and the integration can't work around it.

What's removed

The Example section. It linked to autofac/Examples/tree/master/src/ServiceFabricDemo, and that directory was deleted from the Examples repo — on a branch that has since been renamed from master to main, so the link was dead twice over. Rather than leave a broken link or replace it with meta-commentary about missing content, the section is gone; it should be restored when a current sample lands (tracked separately in the Examples repo).

Deliberately not included

The constructorExceptionCallback signature change from Autofac.ServiceFabric#47 is unreleased, so documenting it now would describe API that isn't on NuGet yet. That belongs with the next release.

Verification

doc8 clean, and a full sphinx -b html build succeeds with every new section rendering correctly. The only build warnings are two pre-existing unknown document: '../troubleshooting/diagnostics' references in faq/container-analysis.rst and lifetime/disposal.rst, unrelated to this change.