Create new module for Spark 3 runner

GIven the big amount of different dependencies and some code incompatibilities introduced by the Spark Structured Streaming runner reliance on the unsable Spark Source V2 API it is a good idea to provide independent modules for the Spark 3 runner.

Notice that the idea is still that the users can provide their Spark dependencies.

We should probably rely on a structure similar to the one the Flink runner uses to support their multiple versions.