fix(docs): merge auth overrides

[kennyderek]

1. previously, if generators.yml had an auth-scheme section, we would:
   a. remove openapi securitySchemes
   b. replace openapi securitySchemes with the singular auth
2. openapi endpoints / global security that referenced the replaced security schemes would not resolve to the correct key

now:

1. if generators.yml had an auth-scheme section
   a. combine the security schemes into a set of security schemes
   b. if openapi has NO global security, then set a global security value using the generators.yml override auth
2. now openapi endpoints referencing openapi specs will resolve, and also generators.yml security will be present globally

[github-actions]

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