Allow selective sql dumps

[Pinolo]

We have a request to allow the same filtering of SQL dumped tables, as offered by drush sql-dump.

We can:

• extend .cloudsql-database-dump and allow to pass a list of table to dump
• offer an alternative job, drupal-specific, which uses drush sql-dump (of course, we would need to use a "tools-like" container to run the command) (I don't know if we even want to add it to this tool, anyway, let's talk!)