Add zero state to "Jobs" page as an experiment

What does this MR do?

Adds the job empty state page as an A/B experiment.

In order to test the page locally, append ?force_experiment=jobs_empty_state to the path, eg: http://localhost:3000/user/project/-/jobs?force_experiment=jobs_empty_state or enter in the console Feature.enable_percentage_of_time(:jobs_empty_state_experiment_percentage, 100).

Screenshot

Control group	Experiment group

Related to #281054 (closed)