This improves the readability of dependencies in the json we
produce for this internally.

- rename #dependencies_list to #internal_dependencies_hash
  - the initial implementation returned an array but now it doesn't
- simplify usage of #tap in #internal_dependencies_hash
- remove safe navigation operator usages in #internal_dependencies_hash
- better document why implicit dependencies are not included in the API JSON
- add new test fixture formula to better test generation of uses from
  macos bounds with the new internal json format