Func<> and custom delegate injection

[dmytroett]

Summary

Implement factory and delegate injection mechanisms in AttributedDI to allow resolving factories/delegates for services (e.g. Func<T> and custom delegate types).

Motivation

• Improve flexibility when constructing services that require runtime parameters.
• Avoid boilerplate factory types in user code while keeping DI-friendly patterns.
• Provide a clear, documented approach that works well with the library's AOP-style registration.

Proposed APIs / Examples

• Direct Func resolution

  • Allow consumers to request Func<IMyService> which returns a new IMyService instance when invoked.

• Delegate generation

  • Support generating delegates that map to service constructors, e.g.:

    public delegate IMyService Create(string param, int val);
    // Container resolves Create -> delegate that constructs/resolves IMyService using provided args

Considerations / Constraints

• Func approach may require generating resolver code per service or inspecting constructors to decide generation; avoid forcing attributes on services if possible.
• Delegate generation must be compatible with common mocking/proxy frameworks (Moq, Castle) to avoid false anti-patterns; determine what limitations exist with dynamic proxying of delegate-returning registrations.
• Decide lifecycle semantics (transient vs scoped/singleton) for factories and produced instances and document them.

Acceptance Criteria

• Support resolving Func<T> from the container.
• Support resolving custom delegates that accept parameters and return service instances.
• Document limitations and compatibility notes with Moq / Castle Proxy and typical testing frameworks.
• Add clear usage examples in README or docs.
• Add tests that verify delegate resolution works and respects service lifetimes.