Move abstract service config to new key

- Moved abstract service factory config to "input_filter_specs" (from
  "input_filters").
- Now registering abstract service factory with InputFilterManager
  configuration, instead of top-level service manager.
Consume InputFilterManager instead of ServiceManager

- Updates the factory to inject the InputFilterManager instead of the
  ServiceManager.
- Updates the listener to rename "services" to "inputFilterManager".
- Tests continue to pass, as we're still composing a
  ServiceLocatorInterface implementation.
CS fixes

- trailing whitespace
Merge branch 'hotfix/input_filters_config_disambiguation'

Close #10