[Consolidate permissions] View pipeline + View Pipeline details

Summary

Consolidate view_pipeline and view_pipeline_details permissions

Reasoning

• These permissions have the same access level: https://docs.gitlab.com/ee/user/permissions.html
• Having fewer permissions groupings will lead to less confusion for customers
• Consolidating permissions before we move full steam ahead with custom roles makes more sense than doing it in the reverse because once we allow customers to opt in or out of permissions on a custom role, it will be more difficult to consolidate permissions in a backwards compatible manner.