Update and rename Setting as feature type

The old Setting["dashboard.emails"] is a Feature Setting, but appeared as
Configuration Setting without button for enable/disable.
In this commit, we update the old setting to behave like a Feature Setting.
Too we rename setting to clarify what emails are blocked with this feature.

app/models/setting.rb

@@ -170,7 +170,7 @@ class Setting < ApplicationRecord
         "hot_score_period_in_days": 31,
         "related_content_score_threshold": -0.3,
         "featured_proposals_number": 3,
-        "dashboard.emails": nil,
+        "feature.dashboard.notification_emails": nil,
         "remote_census.general.endpoint": "",
         "remote_census.request.method_name": "",
         "remote_census.request.structure": "",

config/locales/en/settings.yml

@@ -125,6 +125,9 @@ en:
       valuation_comment_notification: "Valuation comment notification"
       valuation_comment_notification_description: "Send an email to all associated users except valuation commenter to budget investment when a new valuation comment is created"
       graphql_api: "GraphQL API"
+      dashboard:
+        notification_emails: "Dashboard notification emails"
+        notification_emails_description: "Enable sending dashboard notification emails to proposal's authors"
     remote_census:
       general:
         endpoint: "Endpoint"

config/locales/es/settings.yml

@@ -125,6 +125,9 @@ es:
       valuation_comment_notification: "Notificar comentarios de evaluación"
       valuation_comment_notification_description: "Envía un email a todos los usuarios menos al que haya comentado asociados a un presupuesto participativo cuando se cree un nuevo comentario de evaluación"
       graphql_api: "API GraphQL"
+      dashboard:
+        notification_emails: "Emails del panel de progreso"
+        notification_emails_description: "Activar el envío de emails de notificaciones a los autores de las propuestas en la sección de panel de progreso"
     remote_census:
       general:
         endpoint: "Endpoint"