chore: Contact import improvements (#7787)

- Ensure existing contact information is updated on data import
- Refactor the existing job to make it more readable
- Fixes issues with import files in the wrong encoding
fixes: #7307

app/mailers/administrator_notifications/channel_notifications_mailer.rb

@@ -1,16 +1,4 @@
 class AdministratorNotifications::ChannelNotificationsMailer < ApplicationMailer
-  def failed_records(resource)
-    return unless smtp_config_set_or_development?
-
-    subject = 'Contact Import Completed'
-
-    @attachment_url = Rails.application.routes.url_helpers.rails_blob_url(resource.failed_records) if resource.failed_records.attached?
-    @action_url = "#{ENV.fetch('FRONTEND_URL', nil)}/app/accounts/#{resource.account.id}/contacts"
-    @failed_contacts = resource.total_records - resource.processed_records
-    @imported_contacts = resource.processed_records
-    send_mail_with_liquid(to: admin_emails, subject: subject) and return
-  end
-
   def slack_disconnect
     return unless smtp_config_set_or_development?
 
@@ -43,6 +31,19 @@ class AdministratorNotifications::ChannelNotificationsMailer < ApplicationMailer
     send_mail_with_liquid(to: admin_emails, subject: subject) and return
   end
 
+  def contact_import_complete(resource)
+    return unless smtp_config_set_or_development?
+
+    subject = 'Contact Import Completed'
+
+    @action_url = Rails.application.routes.url_helpers.rails_blob_url(resource.failed_records) if resource.failed_records.attached?
+    @action_url ||= "#{ENV.fetch('FRONTEND_URL', nil)}/app/accounts/#{resource.account.id}/contacts"
+    @meta = {}
+    @meta['failed_contacts'] = resource.total_records - resource.processed_records
+    @meta['imported_contacts'] = resource.processed_records
+    send_mail_with_liquid(to: admin_emails, subject: subject) and return
+  end
+
   def contact_export_complete(file_url)
     return unless smtp_config_set_or_development?
 
@@ -56,4 +57,8 @@ class AdministratorNotifications::ChannelNotificationsMailer < ApplicationMailer
   def admin_emails
     Current.account.administrators.pluck(:email)
   end
+
+  def liquid_locals
+    super.merge({ meta: @meta })
+  end
 end