New Alias annotation

[Blacksmoke16]

• Replaces the alias key with a new ADI::AsAlias annotation
  • Accepts alias name as the first positional argument, or if not provided will try to infer it from the included interfaces (modules ending in Interface). If there is only 1, that type is used.
    • A string key may also be provided to alias other concrete services.
• Re-organizes some of the specs to move them into where the logic is actually running

The use case for string keys is you can do something like this:

@[ADI::Register(name: "default_router")]
@[ADI::AsAlias("router")]
class Router
end

To have a service with an internal default_router id, but alias it to a more general router id. Then dependencies can be wired up to depend upon the "@router" implementation. This would allow users to in theory override the router alias to their own implementation (assuming it implements same API/interface(s)), and everything would just pick up on that w/o having to touch the original default_router. I could see this being useful at some point.

Resolves part of #385.