Make OrangeDamApi::getKeywords a pure get function

Problem/Motivation

Currently, OrangeDamApi::getKeywords() retrieves keywords, packages them as OrangeDamKeywordItems and Queues them. The latter two operations should be handled by OrangeDamQueueDataManager.

Since the only two calls to OrangeDamApi:getKeywords() are in OrangeDamQueueDataManager, resolving this is pretty straightforward. This allows OrangeDamApi::getKeywords() to do _only_ what it says on the label, and, once the queueing is moved over to OrangeDamQueueDataManager still allows the application to behave exactly as before.

Proposed resolution

Move the following code to OrangeDamQueueDataManager:

        $this->migrationDataManager->queueMigrationItem($keyword);

Remaining tasks

Create a merge request with the suggested improvement.

User interface changes

Will allow implementors to use OrangeDamApi to just retrieve data, without also queuing it.

API changes

none.

Data model changes

none