Database DDL & Migration Support for plugins

## Is your feature request related to a problem? Please describe

Apache Answer should support a way for plugin devs to have DDL and migration specific to their plugins / code.

There are plenty of use cases for this.
Most basic use cases is their tables would act as meta for their plugins.

## Describe the solution you'd like

Apache Answer should support a way for plugin devs to have DDL and migration specific to their plugins / code.

## Describe alternatives you've considered

Alternative is plugin having its own database. This idea sucks when you have use cases of joins between answer db to plugin db.

No se nombran archivos, pruebas ni puntos de entrada. Empieza por localizar el ciclo de vida de los plugins, el DDL existente de la base de datos y el mecanismo de migración. La tarea estará terminada cuando los desarrolladores de plugins puedan definir y ejecutar cambios de esquema específicos del plugin, manteniendo esas tablas en la base de datos de Apache Answer para realizar joins.

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