Use case: oauth2 access limited time tokens which should be updated on regular basis. Supplier allows us to move refresh logic outside client.
Use specified setter to set up supplier after gitlab api object creation.

Fix #769

Adding branches_to_be_notified to SlackService and deprecating notify_only_default_branch as per
https://docs.gitlab.com/ee/api/services.html#createedit-slack-service

based on docs https://docs.gitlab.com/ee/api/packages.html and inspired by GroupProjectsFilter

Added missing name attribute to Badges class. Also aligned indent of Badges class with rest of api.model package

https://docs.gitlab.com/ee/api/discussions.html#delete-a-merge-request-thread-note

In GitLab 11.11, the Project Hook Key for wiki events was wiki_events.
We don't support GitLab 11.X. We only support GitLab 12.9.2+.
In new version of GitLab the correct key is wiki_page_events.

Since the removal of "X-Total-Pages" and "X-Total" headers, all paginations use the kaminari counter.
In this mode, kaminari counter is reset to -1 during the call of the last page. This part is correct.
Then when we call the `current()` method of the pager to get the current page. This method call the same `page` method than the `next` method. In this method the pager check if there is element before checking if we call for the current page. It throws NoSuchElementException erroneously.

To fix, I change the check sequence. First I check ifthe user call the current page. If so, we return the corresponding items. If not we check if there is such elements and call the API.