Speed Improvement through less looping

[Skipants]

By flattening the loop and only doing YARD parsing once per different list of paths (model vs. controller) we see a significant speedup.

Here's the stats

Before fix:
   bundle exec rails swagger_yard:generate --trace  190.84s user 2.28s system 99% cpu 3:14.88 total
➜ monolith-app ✔ wc artifacts/openapi.json
   10810   23440  317305 artifacts/openapi.json

After fix:
bundle exec rails swagger_yard:generate --trace  6.68s user 1.33s system 92% cpu 8.637 total
➜ monolith-app ✔ wc artifacts/openapi.json
   10810   23440  317305 artifacts/openapi.json

swagger_yard:generate is our rake task that builds the spec and outputs the openapi file to artifacts/openapi.json.
I use wc artifacts/openapi.json to test that the generation is the same.