Refactor POM files to publish in a single workflow

[gopalldb]

Description

Refactoring POM files into a parent POM and child POMs for shaded and thin jars

New structure:

1. new pom.xml which points to parent artefact (databricks-jdbc-parent), this will be published
2. existing pom.xml -> driver/pom.xml for shaded jar (databricks-jdbc), this will be published
3. src -> driver/src, src code had to be moved
4. thin_public_pom.xml -> thin-driver/pom.xml for thin jar (databricks-jdbc-thin), this will be published

Testing

Verified by publishing thin jar

Additional Notes to the Reviewer