OpenAPI: figure out complicated routes

[gr2m]

This is a follow up for #168

• [ ]  figure out how to bring back ignored operations due to route conflicts, see #420. Even if these are fixed for api.github.com, we still need to figure out a way to express these endpoints in OpenAPI for the GHE versions
  • Different URL parameters
    • GET /repos/:owner/:repo/git/refs/:namespace
    • PATCH /repos/:owner/:repo/labels/:current_name
  • Same route, different meaning
    • POST /repos/:owner/:repo/pulls (alternative input)
    • POST /repos/:owner/:repo/pulls/:pull_number/comments (alternative input)
• [ ]  Figure out special case: POST :url is not a relative path but a full URL. See #422