Significantly simplified tests using more fixtures and test facilities already provided by ACA-Py.
Simplified resolver registration/update to be just a simple set. To do a method "addition," controller is responsible for querying the current set and adding to that.
Added awaitable handler helpers
Properly cleanup after pending futures, avoiding a memory leak
Formalize ResolverConnection data structure for use in resolver and routes. Add helpers to the same.
ResolverConnectiondata structure for use in resolver and routes. Add helpers to the same.