Add GraphQL CRUD Mutations for File "Viewed" Persistence
<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=324113) </details> <!--IssueSummary end--> [From this comment](https://gitlab.com/gitlab-org/gitlab/-/issues/322798#note_524582021). Given the [anticipated implementation for the backend](https://gitlab.com/gitlab-org/gitlab/-/issues/322798#note_524066907), the ~frontend will need to add the "CRUD" behavior for connecting to the backend: - "Create" a file review - "Delete" a file review - "Read" the existing file reviews This issue assumes we already [have a GraphQL implementation in the frontend](https://gitlab.com/gitlab-org/gitlab/-/issues/324112).
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