Allow different remote translation keys per tenant

Note we don't need to update the tests; the tests themselves help us
confirm that `Rails.application.secrets` and `Tenant.current_secrets`
return the same object on single-tenant applications.

app/controllers/concerns/remotely_translatable.rb

@@ -26,6 +26,6 @@ module RemotelyTranslatable
     end
 
     def api_key_has_been_set_in_secrets?
-      Rails.application.secrets.microsoft_api_key.present?
+      Tenant.current_secrets.microsoft_api_key.present?
     end
 end

config/secrets.yml.example

@@ -57,7 +57,8 @@ staging:
     # my_tenant_subdomain:
     #   secret_key: my_secret_value
     #
-    # Currently you can overwrite SMTP, SMS and manager settings.
+    # Currently you can overwrite SMTP, SMS, manager and microsoft API
+    # settings.
   <<: *maps
   <<: *apis
 
@@ -92,7 +93,8 @@ preproduction:
     # my_tenant_subdomain:
     #   secret_key: my_secret_value
     #
-    # Currently you can overwrite SMTP, SMS and manager settings.
+    # Currently you can overwrite SMTP, SMS, manager and microsoft API
+    # settings.
   twitter_key: ""
   twitter_secret: ""
   facebook_key: ""
@@ -132,7 +134,8 @@ production:
     # my_tenant_subdomain:
     #   secret_key: my_secret_value
     #
-    # Currently you can overwrite SMTP, SMS and manager settings.
+    # Currently you can overwrite SMTP, SMS, manager and microsoft API
+    # settings.
   twitter_key: ""
   twitter_secret: ""
   facebook_key: ""

lib/remote_translations/microsoft/available_locales.rb

@@ -36,7 +36,7 @@ class RemoteTranslations::Microsoft::AvailableLocales
       uri = URI(host + path)
 
       request = Net::HTTP::Get.new(uri)
-      request["Ocp-Apim-Subscription-Key"] = Rails.application.secrets.microsoft_api_key
+      request["Ocp-Apim-Subscription-Key"] = Tenant.current_secrets.microsoft_api_key
 
       response = Net::HTTP.start(uri.host, uri.port, use_ssl: uri.scheme == "https") do |http|
         http.request(request)

lib/remote_translations/microsoft/client.rb

@@ -6,7 +6,7 @@ class RemoteTranslations::Microsoft::Client
   PREVENTING_TRANSLATION_KEY = "notranslate".freeze
 
   def initialize
-    api_key = Rails.application.secrets.microsoft_api_key
+    api_key = Tenant.current_secrets.microsoft_api_key
     @client = TranslatorText::Client.new(api_key)
   end