Allow for varied PostgreSQL 10+ publication modes

Taken from the discussion https://gitter.im/debezium/user?at=5d88e46556677e767a45d5ac

The idea is to introduce a new configuration option, perhaps publication.autocreate.mode that is backed by an Enum of:

DISABLED
The connector will not attempt to create a publication at all. The expectation is that the user has created the publication up-front. If the publication isn't found to exist upon startup, the connector will throw an exception and stop.

ALL_TABLES
This acts like the current behavior where if the publication does not exist the connector will create the publication for all tables. If the publication exists, we will use it.

EMPTY
This mode creates the publication based on the configured name; however the publication will be created with no tables assigned to it. If the publication exists, we will use it as-is. The expectation is that users would alter the publication later, perhaps as part of an integration/deployment step. From Debezium's perspective, we are not concerned about what tables ultimately are linked to the publication, simply the publication name reference itself.