Dbt-vertica

- Added support for snapshot timestamp with passing tests
- Added support for snapshot check cols with passing tests

- Fixed the Incremental method implementation (was buggy/incomplete)
- Removed the `unique_id` as it wasn't implemented
- Fixed when no fields were added - full table merge
- Added testing for Incremental materialization
- Testing for dbt Incremental full table
- Testing for dbt Incremental specified merged columns
- Added more logging to the connector to help understand why tests were failing
- Using the official [Vertica CE 11.0.x docker image](https://hub.docker.com/r/vertica/vertica-ce) now for tests

- Add support for DBT version 1.0.0

- Add testing, fix schema drop.

- Add `unique_field` property on connection, supporting 0.21.x.

- Added SSL options.