Replace apivore with rswag for api tests (#969)

* Replace apivore api tests with rswag
* move to OpenAPI Spec 3.0.1
* a swagger UI is now reachable at http://localhost:3000/api-docs/index.html
*  swagger file is generated by running  `RAILS_ENV=test rails rswag`
    and it was moved from /docs/swagger.v1.yml to /swagger/v1/swagger.yml

---------

Co-authored-by: viehlieb <pf@pragma-shift.net>

config/initializers/rswag_api.rb

@@ -0,0 +1,13 @@
+Rswag::Api.configure do |c|
+  # Specify a root folder where Swagger JSON files are located
+  # This is used by the Swagger middleware to serve requests for API descriptions
+  # NOTE: If you're using rswag-specs to generate Swagger, you'll need to ensure
+  # that it's configured to generate files in the same folder
+  c.swagger_root = Rails.root.to_s + '/swagger'
+
+  # Inject a lambda function to alter the returned Swagger prior to serialization
+  # The function will have access to the rack env for the current request
+  # For example, you could leverage this to dynamically assign the "host" property
+  #
+  # c.swagger_filter = lambda { |swagger, env| swagger['host'] = env['HTTP_HOST'] }
+end