Single module/assembly for both source and sink connectors

# What is currently missing?

There's not much benefit to separating the source and sink connectors into different jars:
- it complicates the structure of the repo and the build,
- we're currently generating a full 94MB assembly for each connector even though they have a majority of duplicated dependencies (99% shared DNA!)

# How could this be improved?

Consider a single module (or module-less) maven project with the classes separated by package instead of into separate jars and a single assembly

# Is this a feature you would work on yourself?

* [ ] I plan to open a pull request for this feature