Positioning cycle analytics stages

What does this MR do?

Allow ordering of Cycle Analytics stages

• Add RelativePositioning module to the stage classes.
• Allow the positioning parameters to be passed in the controller to the update service.
• Update the order of stages within the update service.

For the API, there are two optional parameters for the PUT /stages/:id endpoint (stage update):

• move_after_id - When moving down, pass the id of the stage above of the dragged stage.
• move_before_id - When moving up, pass the id of the stage below of the dragged stage.

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.