Add further missing GraphQL Data for pipeline details

What does this MR do and why?

This MR adds some Ci::Pipeline fields to the GraphQL API in order to enable the frontend have one source of truth in their code

How to set up and validate locally

1. Start up Gitlab locally
2. Find a Pipeline that you want to query from the Rails console and get its' iid as well as the project's full_path
3. Open GraphiQL explorer and query the pipeline's newly added fields

Example query:

{
  project(fullPath: "i-user-1-1702907951/Wget2") {
    id
    pipeline(iid: 1) {
      # new fields
      yamlErrors
      trigger
    }
  }
}

Related to #433244 (closed)