Migrate tx_ter_extensionqueue to TER v2
The table tx_ter_extensionqueue has a TCA which is completely unneeded.
In addition, it is only used in two places, in the SOAP API (when an extension has been uploaded) and in a scheduler task to process an uploaded extension.
I suggest to:
- Remove the TCA definition and only keep this is as a DB table with necessary fields (uid, createdon=timestamp, extensionkey, extensiondetailsid, processedon=timestamp or null)
- We then do not put this into a Repository class in EXT:terfe2, but like a QueueProcessingStack class with a "->getNextQueueItem()" and a "->markAsProcessed()" and direct Doctrine DBAL queries. We then change the code within tx_ter_api to just use the new API and make tx_ter a bit smaller again.