Communication between translate5 installations

One translate5 instance should be the source instance, another one the target instance.

On the source instance, the targets should be configured similar to users - since a target instance for external editing behaves in the workflow similar as a user.

From the source instance the target instance is a blackbox. Yet, the workflow steps must be synchronized from source to target, so that if target instance is used in source as "review 2",  this is reflected  to the target - for correct auto assignments etc.

In the source system such a workflow step has a status external processing, so that the whole task is locked.

The target system must provide the URL, a user (which is assigned in the target system with a customer with corresponding defaults etc).

Multiple steps on source can be handled by task update on the target, since task is identified with foreignId in target.

For the transferred data TRANSLATE-3117 is a precondition. Additionally to the data, the desired initial workflow step is pushed to the source system. Because of the used pseudo-user  a customer is chosen, and based on this customer the users and language resources assigned as default are assigned automatically, even for workflow steps, that are not transferred from the source system. These steps then belong to the target system and the workflow runs as usual, even if there are steps before the workflow steps coming from the source system. Yet transferred back will only be the steps coming from the source system.

TMX files must be addable and imported to a task as it already works for TBX files, and removed on task deletion afterwards.

On workflow end in target system: the source is called via callback URL which then pulls the task and applies changes via update xlf.

Fixes TrackChanges Update XLF

The normal xlf 1.2 ex and import must be able to export trackchanges in t5 namespaced tags, same for import. Merging of changes is done then in UI as usual.

The users of source must be transferred anonymously to target source/user1 etc. and added there to the user per task list. Same on the way back, where the users used in target go back as anonymous users into the source.

On Update xliff in the import no new trackchanges needs to be added, but only the xliff contents must be updated, since all trackchanges from source and target system are already contained in the segment.