What does this MR do?
Improved the importer to have the paging cached as descibed in #276443
Furthermore we improved the client and the objects to be more concise and reusable. We introduced three new objects to have a better representation of the Bitbucket Server API.
first separation for !47138 (closed)
Does this MR meet the acceptance criteria?
Documentation (if required)
Code review guidelines
Merge request performance guidelines
Separation of EE specific content