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_ui.rb

@@ -0,0 +1,15 @@
+Rswag::Ui.configure do |c|
+  # List the Swagger endpoints that you want to be documented through the
+  # swagger-ui. The first parameter is the path (absolute or relative to the UI
+  # host) to the corresponding endpoint and the second is a title that will be
+  # displayed in the document selector.
+  # NOTE: If you're using rspec-api to expose Swagger files
+  # (under swagger_root) as JSON or YAML endpoints, then the list below should
+  # correspond to the relative paths for those endpoints.
+
+  c.swagger_endpoint '/api-docs/v1/swagger.yaml', 'API V1 Docs'
+
+  # Add Basic Auth in case your API is private
+  # c.basic_auth_enabled = true
+  # c.basic_auth_credentials 'username', 'password'
+end