Add pipelineScheduleTakeOwnership mutation

What does this MR do and why?

Adds missing GraphQL functionality: ability to take ownership of a pipeline schedule via GraphQL

Will be used in refactor &6189 (closed) to move the pipelines schedule feature to Vue/GraphQL.

Screenshots or screen recordings

How to set up and validate locally

1. Create pipeline schedules
2. Run mutation impersonating another user who has correct access rights to project (maintainer)
3. Confirm mutation takes over pipeline to new user
4. Also run mutation impersonating another user who does not have rights (reporter)
5. Confirm error and the ownership did not take affect

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #378202 (closed)