Pipeline GraphQL Conversion Part I

What does this MR do?

This add the :graphql_pipeline_details feature flag as preparation for further work on #223262. It also improves the pipeline_details_bundle.js by removing the DOMContentLoaded call (see: &4541 (closed)) and by conditionally importing components behind the feature flags.

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines
• Merge request performance guidelines
• Style guides

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.