Summary:
- added functionality to `GraphDbAccessor` for cardinality estimates
- changed all `GraphDbAccessor::Count...` functions to return `int64_t`
- added the need functionality into `LabelPropertyIndex`
- modified `SkipList::position_and_count` to accept a custom `equals` function. Equality could not be implemented using only the custom `less` because it compares a templated `TItem` with skiplist element type `T`, and is therefore not symetrical.
Reviewers: teon.banek, buda, mislav.bradac
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D521
Summary:
- refactored so `less` is used instead of `greater`
- added a fuzzy unit test
Reviewers: mislav.bradac, buda, teon.banek
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D519
