feat: Add language selector

Closes #212

client/src/sagas/core/services/user.js

@@ -1,6 +1,7 @@
 import { call, put, select } from 'redux-saga/effects';
 
 import { logoutService } from './login';
+import { changeCoreLanguageService } from './core';
 import request from '../request';
 import { currentUserIdSelector, currentUserSelector, pathSelector } from '../../../selectors';
 import {
@@ -81,6 +82,21 @@ export function* handleUserUpdateService(user) {
   yield put(handleUserUpdate(user, users, isCurrent));
 }
 
+// TODO: add loading state
+export function* updateUserLanguageService(id, language) {
+  yield call(changeCoreLanguageService, language);
+
+  yield call(updateUserService, id, {
+    language,
+  });
+}
+
+export function* updateCurrentUserLanguageService(language) {
+  const id = yield select(currentUserIdSelector);
+
+  yield call(updateUserLanguageService, id, language);
+}
+
 export function* updateUserEmailService(id, data) {
   yield put(updateUserEmail(id, data));