Allow to choose which method to use when syncing feature branches: merge or rebase.

When using 'git rebase master' command in feature branch instead of 'git merge master', we'll get a linear history in feature branch, which is widely used in development, and considered a better way than lot of merging.

Latest update from Atlassian 2024-09-30

Rebasing is now available as an option when syncing feature branches on pull requests, as well as at merge time. https://bitbucket.org/blog/branch-sync-merge-rebase