Switched frontend i18n requires to go through proxy

- we export i18n from `core/frontend/services/proxy` and this is used in
  the most of the places in the frontend code
- this commit aligns the rest of the code in core/frontend to use the
  proxy too
- unfortunately core/frontend/services/themes/i18n.js loops back to the
  proxy so we have a circular dependency

core/frontend/apps/amp/lib/helpers/amp_content.js

@@ -9,12 +9,7 @@
 const Promise = require('bluebird');
 
 const moment = require('moment');
-const proxy = require('../../../../services/proxy');
-const SafeString = proxy.SafeString;
-const logging = proxy.logging;
-const i18n = proxy.i18n;
-const errors = proxy.errors;
-const urlUtils = proxy.urlUtils;
+const {SafeString, logging, i18n, errors, urlUtils} = require('../../../../services/proxy');
 const amperizeCache = {};
 let allowedAMPTags = [];
 let allowedAMPAttributes = {};

core/frontend/apps/amp/lib/router.js

@@ -3,7 +3,7 @@ const express = require('../../../../shared/express');
 const ampRouter = express.Router('amp');
 
 // Dirty requires
-const {i18n} = require('../../../../server/lib/common');
+const {i18n} = require('../../../services/proxy');
 const errors = require('@tryghost/errors');
 
 const urlService = require('../../../services/url');

core/frontend/apps/private-blogging/index.js

@@ -1,4 +1,4 @@
-const {i18n} = require('../../../server/lib/common');
+const {i18n} = require('../../services/proxy');
 const urlUtils = require('../../../shared/url-utils');
 const logging = require('../../../shared/logging');
 const errors = require('@tryghost/errors');

core/frontend/apps/private-blogging/lib/middleware.js

@@ -6,7 +6,7 @@ const path = require('path');
 const config = require('../../../../shared/config');
 const urlUtils = require('../../../../shared/url-utils');
 const constants = require('@tryghost/constants');
-const {i18n} = require('../../../../server/lib/common');
+const {i18n} = require('../../../services/proxy');
 const errors = require('@tryghost/errors');
 const settingsCache = require('../../../../server/services/settings/cache');
 // routeKeywords.private: 'private'

core/frontend/services/routing/controllers/collection.js

@@ -1,6 +1,6 @@
 const _ = require('lodash');
 const debug = require('ghost-ignition').debug('services:routing:controllers:collection');
-const {i18n} = require('../../../../server/lib/common');
+const {i18n} = require('../../proxy');
 const errors = require('@tryghost/errors');
 const security = require('@tryghost/security');
 const urlService = require('../../url');

core/frontend/services/settings/ensure-settings.js

@@ -2,7 +2,7 @@ const fs = require('fs-extra');
 const Promise = require('bluebird');
 const path = require('path');
 const debug = require('ghost-ignition').debug('frontend:services:settings:ensure-settings');
-const {i18n} = require('../../../server/lib/common');
+const {i18n} = require('../proxy');
 const errors = require('@tryghost/errors');
 const config = require('../../../shared/config');
 

core/frontend/services/settings/loader.js

@@ -1,7 +1,7 @@
 const fs = require('fs-extra');
 const path = require('path');
 const debug = require('ghost-ignition').debug('frontend:services:settings:settings-loader');
-const {i18n} = require('../../../server/lib/common');
+const {i18n} = require('../proxy');
 const errors = require('@tryghost/errors');
 const config = require('../../../shared/config');
 const yamlParser = require('./yaml-parser');

core/frontend/services/settings/validate.js

@@ -1,6 +1,6 @@
 const _ = require('lodash');
 const debug = require('ghost-ignition').debug('frontend:services:settings:validate');
-const {i18n} = require('../../../server/lib/common');
+const {i18n} = require('../proxy');
 const errors = require('@tryghost/errors');
 const themeService = require('../themes');
 const _private = {};

core/frontend/services/settings/yaml-parser.js

@@ -1,6 +1,6 @@
 const yaml = require('js-yaml');
 const debug = require('ghost-ignition').debug('frontend:services:settings:yaml-parser');
-const {i18n} = require('../../../server/lib/common');
+const {i18n} = require('../proxy');
 const errors = require('@tryghost/errors');
 
 /**

core/frontend/services/themes/handlebars/template.js

@@ -3,7 +3,7 @@ const templates = {};
 const _ = require('lodash');
 const errors = require('@tryghost/errors');
 const hbs = require('../engine');
-const {i18n} = require('../../../../server/lib/common');
+const {i18n} = require('../../proxy');
 
 // Execute a template helper
 // All template helpers are register as partial view.

core/frontend/services/themes/index.js

@@ -1,6 +1,7 @@
 const _ = require('lodash');
 const debug = require('ghost-ignition').debug('themes');
-const {events, i18n: commonI18n} = require('../../../server/lib/common');
+const {events} = require('../../../server/lib/common');
+const {i18n: commonI18n} = require('../proxy');
 const logging = require('../../../shared/logging');
 const errors = require('@tryghost/errors');
 const themeLoader = require('./loader');

core/frontend/services/themes/middleware.js

@@ -2,7 +2,7 @@ const _ = require('lodash');
 const hbs = require('./engine');
 const urlUtils = require('../../../shared/url-utils');
 const config = require('../../../shared/config');
-const {i18n} = require('../../../server/lib/common');
+const {i18n} = require('../proxy');
 const errors = require('@tryghost/errors');
 const settingsCache = require('../../../server/services/settings/cache');
 const labs = require('../../../server/services/labs');

core/frontend/services/themes/storage.js

@@ -8,7 +8,7 @@ const themeLoader = require('./loader');
 const toJSON = require('./to-json');
 
 const settingsCache = require('../../../server/services/settings/cache');
-const {i18n} = require('../../../server/lib/common');
+const {i18n} = require('../proxy');
 const logging = require('../../../shared/logging');
 const errors = require('@tryghost/errors');
 const debug = require('ghost-ignition').debug('api:themes');

core/frontend/services/themes/validate.js

@@ -2,7 +2,7 @@ const _ = require('lodash');
 const Promise = require('bluebird');
 const fs = require('fs-extra');
 const config = require('../../../shared/config');
-const {i18n} = require('../../../server/lib/common');
+const {i18n} = require('../proxy');
 const errors = require('@tryghost/errors');
 
 const canActivate = function canActivate(checkedTheme) {