Remove exports/base controller in favor of shared concern (#3444)

spec/controllers/settings/exports/base_controller_spec.rb

@@ -1,29 +0,0 @@
-# frozen_string_literal: true
-
-require 'rails_helper'
-
-describe Settings::Exports::BaseController do
-  controller do
-    def export_data
-      @export.account.username
-    end
-  end
-
-  describe 'GET #index' do
-    it 'returns a csv of the exported data when signed in' do
-      user = Fabricate(:user)
-      sign_in user
-      get :index, format: :csv
-
-      expect(response).to have_http_status(:success)
-      expect(response.content_type).to eq 'text/csv'
-      expect(response.headers['Content-Disposition']).to eq 'attachment; filename="base.csv"'
-      expect(response.body).to eq user.account.username
-    end
-
-    it 'returns unauthorized when not signed in' do
-      get :index, format: :csv
-      expect(response).to have_http_status(:unauthorized)
-    end
-  end
-end