Cycle in `projection` -> `convert` (`convert.Jsr310Converters`) -> `mapping` -> `projection`

[mp911de]

With the introduction of entity projections we introduced a package cycle. The project package uses Jsr310Converters which could be moved either out of the package or we could move EntityProjectionIntrospector into the projection package as it already has access to convert.

/cc @meistermeier

[schauder]

[schauder]

Just moving Jsr310Converters wouldn't help, since it depends on ReadingConverter and WritingConverter.

Moving EntityProjectionIntrospector to projection together with EntityProjection sounds like the right thing to do.

[mp911de]

Makes sense since it's a new API. Requires subsequent changes in MongoDB (main) and Cassandra (once merged).