Add interop test agent
The new stack-pass ObjectMethodProxyGenerator emits proxies that derive
from Opc.Ua.ObjectTypeClient and reference Session.MessageContext.NamespaceUris.
Neither type exists in the in-memory test compilation, which only references
Opc.Ua.Types.dll. Moving ObjectTypeClient to Opc.Ua.Types would cascade ISessionClient,
IClientBase, ITransportChannel and the generated service interfaces with it, so the
type stays in Opc.Ua.Core and we add a minimal stub to OpcUaCoreStubs instead.
Wire Microsoft.Extensions.Options 10.0.5 + DependencyInjection.Abstractions 10.0.5 into Directory.Packages.props and the Gds.Client.Common project to enable upcoming options-driven configuration work.
Modernize Opc.Ua.Gds.Client.Common (DI, options, interfaces, async dispose)
Generate stack and application code using source generators
Change built in types to readonly structs
Update localized text implementation to use JSON text serializer
Status code with symbolic names
Immutable node ids
No boxing for all built in types <= 8 bytes in Variant.
Split user identity token and token handling via token handler
Add migration guide for breaking changes