PipelineScheduleService return error

What does this MR do and why?

This MR addresses the first 2 of 4 follow-up issues created from !97857 (closed)

PipelineScheduleService was returning nil when project did not exist. This MR updates the service to return a ServiceResponse error instead.

Updates service authorization to align with Permission Development Guildlines. Adds ability check for current_user on :play_pipeline_schedule.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Open rails console(include Factory bot for easy creation of objects needed to test) create: a. a new project b. a Ci:PipelineSchedule with that project with the project user as the owner
2. Delete the Project (created in 1a)
3. Call PipelineScheduleService with the schedule created in step 1b
4. Observe the service returns a ServiceResponse.error

 # Load a rails console:
 $ bundle exec rails console

# Once console has loaded:

 include FactoryBot::Syntax::Methods
 project = create(:project)
 pipeline_schedule = create(:ci_pipeline_schedule, project: project, owner: project.creator)
 project.destroy
 Ci::PipelineScheduleService.new(project, project.creator).execute(pipeline_schedule)

Related to #385579