v0.5.2

Full Changelog: 0.5.0...0.5.2

This release is a patch release since there is no breaking change on the surface level but under the hood we have moved all worker management logic up from the stream level to the target level creating much more intuitive worker pool. Architecturally, it simplifies all of the sink implementations as can be observed in the code. This also includes general improvements in the storage write API implementation and dynamic protocol buffer schema generation. The worker pool by default is based on CPU cores.