bitbucketserver: Implement LoadPullRequestActivities
Created by: tsenart
This method is needed in the context of a8n to load all activity that happened in a PR. These activities will later be converted into ChangesetEvents.
Part of #6085
Created by: tsenart
This method is needed in the context of a8n to load all activity that happened in a PR. These activities will later be converted into ChangesetEvents.
Part of #6085