Fix bugs uncovered by v2 API test coverage

These changes resolve the following issues uncovered via the API v2 tests:

- app/views/api/v2/datasets/_show.json.jbuilder
  - Failure rendering output.doi_url when output is present (undefined method `doi_url`)
- config/routes.rb
  - Spec failures due to undefined route helpers in test context (e.g., `api_v2_templates_path`)

Author: aaronskiba

app/views/api/v2/datasets/_show.json.jbuilder

@@ -7,7 +7,6 @@ if output.is_a?(ResearchOutput)
 
   json.type output.output_type
   json.title output.title
-  json.doi_url output.doi_url
   json.description output.description
   json.personal_data Api::V2::ApiPresenter.boolean_to_yes_no_unknown(value: output.personal_data)
   json.sensitive_data Api::V2::ApiPresenter.boolean_to_yes_no_unknown(value: output.sensitive_data)

config/routes.rb

@@ -210,6 +210,7 @@
       get :me, controller: :base_api
 
       resources :plans, only: %i[index show]
+      resources :templates, only: :index
     end
   end