Submitted by: @mrotteveel

JDBC527 added support for database encryption callback support with a static reply. Introduce support for database encryption callback plugins so database encryption plugins that require a dynamic response to a challenge can be supported as well.

The initial implementation already has a starting point, but we need to refine this further and make the implementation really pluggable. This may share part of the work with authentication plugin support.

Tentatively scheduled for Jaybird 4, may be deferred to Jaybird 5.