Cross DB Transforms

**What problem will this feature request solve?**
Use a different engine for transforms to write to

**Describe the solution you'd like.**
Allow a transform to write to different target DB engine than source DB engine

**How does this feature request impact you?**
Requested by a trialer

The issue names no files, tests, or transform entry points. Start by locating the transform implementation and database adapter paths, then determine how source and target engines are represented. Done should include a defined cross-engine transform flow and tests covering the supported source and target combinations.

Written by the indexing model from the issue text.