Summary:
Generate conversion functions from C++ enum to Cap'n Proto and vice
verse. This should reduce the generated code size and hopefully improve
readability.
Use conversion functions for enums in default serialization generation.
`capnp-save-enum` and `capnp-load-enum` should now be used exclusively
to serialize non LCP defined enumerations. They now always require
`enum-values` argument.
Reviewers: mtomic, llugovic
Reviewed By: mtomic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1696