Feature: Allow staff to change user emails (#7074)

* Admin: Show unconfirmed email address on account page

* Admin: Allow staff to change user email addresses

* ActionLog: On change_email, log current email address and new unconfirmed email address

app/controllers/admin/change_emails_controller.rb

@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+module Admin
+  class ChangeEmailsController < BaseController
+    before_action :set_account
+    before_action :require_local_account!
+
+    def show
+      authorize @user, :change_email?
+    end
+
+    def update
+      authorize @user, :change_email?
+
+      new_email = resource_params.fetch(:unconfirmed_email)
+
+      if new_email != @user.email
+        @user.update!(
+          unconfirmed_email: new_email,
+          # Regenerate the confirmation token:
+          confirmation_token: nil
+        )
+
+        log_action :change_email, @user
+
+        @user.send_confirmation_instructions
+      end
+
+      redirect_to admin_account_path(@account.id), notice: I18n.t('admin.accounts.change_email.changed_msg')
+    end
+
+    private
+
+    def set_account
+      @account = Account.find(params[:account_id])
+      @user = @account.user
+    end
+
+    def require_local_account!
+      redirect_to admin_account_path(@account.id) unless @account.local? && @account.user.present?
+    end
+
+    def resource_params
+      params.require(:user).permit(
+        :unconfirmed_email
+      )
+    end
+  end
+end