Fix bugs uncovered by v2 API test coverage

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

- app/views/api/v2/_standard_response.json.jbuilder
  - Failure rendering json.client when @client is nil (undefined method `name` for nil)
- app/views/api/v2/datasets/_show.json.jbuilder
  - Failure rendering output.doi_url when output is present (undefined method `doi_url`)
- app/views/api/v2/templates/index.json.jbuilder
  - Failure in mapping template_ids when some nested keys are nil (undefined method `[]` for nil)
- 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/_standard_response.json.jbuilder

@@ -15,7 +15,7 @@ json.ignore_nil!
 json.server @server
 json.source "#{request.method} #{request.path}"
 json.time Time.now.to_formatted_s(:iso8601)
-json.client @client.name
+json.client @client&.name
 json.code response.status
 json.message Rack::Utils::HTTP_STATUS_CODES[response.status]
 

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)

app/views/api/v2/templates/index.json.jbuilder

@@ -17,7 +17,7 @@ json.items @items do |template|
     end
 
     json.template_id do
-      identifier = Api::V2::ConversionService.to_identifier(context: @application,
+      identifier = Api::V2::ConversionService.to_identifier(context: @server,
                                                             value: template.id)
       json.partial! 'api/v2/identifiers/show', identifier: identifier
     end

config/routes.rb

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