Resolve #11: Use Func<X, Y> to handle methods with parameters.

[tillig]

Added the test for #11 and, for the case of methods with generic parameters, switched the ResolvingInterceptor to dynamically create a Func<X, Y> delegate type based on the parameter types and return type for the method, then use that resolved factory for the method backing.

The biggest challenge around generic parameters is that, while you might have OpenGenericImpl<string> as a parameter, someone could also do public class MyClosed : OpenGenericImpl<string> and pass one of those as the parameter, so you get into type casting and compatibility challenges... which we've already solved in core Autofac. Hence the desire to reuse that logic and not mirror it here.

I didn't add caching for the Func<X, Y> type signature; we'd need to add method caching and matching logic something similar to the constructor caching and matching in core Autofac which seemed a little overkill here. It does mean for every method invocation (for methods with generic parameters) it's two resolution calls - one to get the factory, one to get the resolved object. Not sure if that's acceptable, but it seemed the simplest way to add support to for open generic methods/parameters.

I did leave the original logic for methods that don't have generic parameters so it's still reasonably optimal.

Generic return types don't appear to have any impact here, so there was no special requirement or change to handle that.

[tillig]

Looks like I'll need to add a test for that exception condition.

[codecov]

Codecov Report

Merging #12 (cf792a5) into develop (870c783) will increase coverage by 0.38%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop      #12      +/-   ##
===========================================
+ Coverage    97.87%   98.26%   +0.38%     
===========================================
  Files            4        4              
  Lines           94      115      +21     
  Branches        17       18       +1     
===========================================
+ Hits            92      113      +21     
  Misses           1        1              
  Partials         1        1              

Impacted Files	Coverage Δ
...ac.Extras.AggregateService/ResolvingInterceptor.cs	97.36% <100.00%> (+1.00%)	⬆️

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[alistairjevans]

Looks good, and I agree it's the right choice to delegate the generic parameter logic to Autofac via the Func<> call. The open generic path you've added is not going to be very performant, but this generic argument stuff rarely is.