Mostly using autowiring to inject deps.
The only tricky part was for import because all producer use the same class and have a different alias. So we must write them down in the service definition, autowiring doesn't work in that case.
Usually:
- if a controller has a constructor, it means injected services are at least re-used once in actions
- otherwise, service are injected per action
- Adds a new `search` key to `src/Wallabag/ApiBundle/Resources/config/routing_rest.yml`
- Reuses the `getBuilderForSearchByUser` method from the EntryRepository
- Supports, `term`, `page`, and `perPage` query parameters
- Some very basic tests
