Implement dependencies GraphQL endpoint

Why are we doing this work

The dependency list currently uses a private REST API (the dependencies controller), in order to fetch dependency data. This causes us to duplicate code with the dependencies API

Proposal:

1. Implement a GraphQL resolver for dependencies
2. Use a feature flag to toggle between dependencies controller and the GraphQL API on the frontend (#393061 (closed))

Relevant links

Non-functional requirements

• Documentation:
• Feature flag:
• Performance:
• Testing:

Implementation plan

Verification steps

1. Go to https://gitlab.com/-/graphql-explorer

2. Submit this graphQL query:

   query {
     project(fullPath: "gitlab-org/gitlab") {
       dependencies {
         nodes {
           id
           name
           version
           location {
             path
             blobPath
           }
         }
       }
     }
   }

Note that location data is currently null because dependency scanning is not providing it correctly in the SBoM.