Frontend: Rename Pipeline Mini Graph

What does this MR do and why?

Part 1 for #384853

This is just a file rename MR. There are 0 changes to code logic.

THIS MR

• Rename pipeline_mini_graph.vue > legacy_pipeline_mini_graph.vue
• Rename graphql_pipeline_mini_graph.vue > pipeline_mini_graph.vue

UPCOMING MRs

• Rename pipeline_stage.vue > legacy_pipeline_stage.vue

• Add in a new pipeline_stage.vue for GraphQL data

• Rename pipeline_mini_graph/job_item.vue > pipeline_mini_graph/legacy_job_item.vue

• Add in a new job_item.vue for GraphQL data

• Add in code/logic for fetching stage by ID

• Remove the formattedStages portion of pipeline_mini_graph.vue because this will no longer be needed.

• Update specs

Screenshots or screen recordings

No UI changes

How to set up and validate locally

1. Feature flag - Feature.enable(:ci_graphql_pipeline_mini_graph)
2. Navigate to any commit page
3. Insure that the pipeline mini graph functions the same
4. Navigate to the pipeline editor
5. Insure that the pipeline mini graph functions the same

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.