[Feature] Ability to import and export Buggregator messages

[roxblnfk]

I think it would be useful to have the ability to export (save) and import (load) dumps and other Buggregator messages. Developers could attach such dumps to issues in their bug trackers.

[Kreezag]

Our current events are stored on the server side in the DB, so we firstly need to prepare BE endpoints to apply buggregator messages. @butschster should we move this issue to the buggregator/server repo?