Store environment CI configuration for new jobs

What does this MR do and why?

Link jobs to environment on creation

When a CI job references an environment (it uses the environment keyword in the CI template) a new Environments::Job record is created to persist a link to the environment.

Records are created for both Build and Bridge job types, for new jobs and retries of existing jobs.

The new behaviour is controlled by the persisted_job_environment_relationship feature flag.

References

#552372 (closed)

How to set up and validate locally

1. Enable the persisted_job_environment_relationship feature flag.
2. Execute any CI job that references an environment, for example:

   example-job:
     script: echo test
     environment: production

3. From the Rails console, verify that the record was created: Ci::Build.find(<job ID>).job_environment
4. Retry the job, and perform the same verification (with the new job ID)

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