Unify CallableResolver and AdvancedCallableResolver

[l0gicgate]

Since AdvancedCallableResolver was introduced midway through the release of Slim 4, we will need to unify the two interfaces in Slim 5 and break everything moving forward.

We will also need to ensure that the CallableResolverInterface::resolve() method throws a named exception instead of RuntimeException so downstream implementers can effectively control the execution flow.

[ddrv]

@l0gicgate make 5.x branch please so that interested contributors can send pull requests

[l0gicgate]

@ddrv I do not have the bandwidth to maintain 3 branches. The Slim 4 docs are still in somewhat abysmal shape. Creating a Slim 5 branch right now would be a ton of extra work with very little upside. I appreciate the eagerness to get this going but I don't think the timing is adequate right now.