Add file upload delete endpoint

What does this MR do and why?

Allows deleting file upload in a project or group.

• only maintainers/owners can delete project/group uploads - #366406 (comment 1031704145)

Related to #366406 (closed)

Sample query:

mutation {
  uploadDelete(input: {projectPath: "flightjs/flight", secret: "84ef8229da63c0204efe642528cac8e1", filename: "sample.txt"}) {
    upload {
      id
      size
      path
    }
    errors
  }
}

DB query

https://postgres.ai/console/gitlab/gitlab-production-tunnel-pg12/sessions/11091/commands/39684

Note that path doesn't match "real" path on prod.

SELECT "uploads".*
FROM "uploads"
WHERE "uploads"."model_type" = 'Project'
  AND "uploads"."model_id" = 278964
  AND "uploads"."uploader" = 'FileUploader'
  AND "uploads"."path" IN ('f82d4cf7eccaa782b83682a48c787244/sample.txt',
                           '@hashed/e7/f6/e7f6c011776e8db7cd330b54174fd76f7d0216b612387a5ffcfb81e6f0919683/f82d4cf7eccaa782b83682a48c787244/sample.txt')
LIMIT 1

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