feat: I18n (#1653)

* feat: i18n

* Changing language single source of truth from TEAM to USER

* Changes according to @tommoor comments on PR

* Changed package.json for build:i18n and translation label

* Finished 1st MVP of i18n for outline

* new translation labels & Portuguese from Portugal translation

* Fixes from PR request

* Described language dropdown as an experimental feature

* Set keySeparator to false in order to cowork with html keys

* Added useTranslation to Breadcrumb

* Repositioned <strong> element

* Removed extra space from TemplatesMenu

* Fortified the test suite for i18n

* Fixed trans component problematic

* Check if selected language is available

* Update yarn.lock

* Removed unused Trans

* Removing debug variable from i18n init

* Removed debug variable

* test: update snapshots

* flow: Remove decorator usage to get proper flow typing
It's a shame, but hopefully we'll move to Typescript in the next 6 months and we can forget this whole Flow mistake ever happened

* translate: Drafts

* More translatable strings

* Mo translation strings

* translation: Search

* async translations loading

* cache translations in client

* Revert "cache translations in client"

This reverts commit 08fb61ce36384ff90a704faffe4761eccfb76da1.

* Revert localStorage cache for cache headers

* Update Crowdin configuration file

* Moved translation files to locales folder and fixed english text

* Added CONTRIBUTING File for CrowdIn

* chore: Move translations again to please CrowdIn

* fix: loading paths
chore: Add strings for editor

* fix: Improve validation on documents.import endpoint

* test: mock bull

* fix: Unknown mimetype should fallback to Markdown parsing if markdown extension (#1678)

* closes #1675

* Update CONTRIBUTING

* chore: Add link to translation portal from app UI

* refactor: Centralize language config

* fix: Ensure creation of i18n directory in build

* feat: Add language prompt

* chore: Improve contributing guidelines, add link from README

* chore: Normalize tab header casing

* chore: More string externalization

* fix: Language prompt in dark mode

Co-authored-by: André Glatzl <andreglatzl@gmail.com>

package.json

@@ -5,11 +5,12 @@
   "main": "index.js",
   "scripts": {
     "clean": "rimraf build",
+    "build:i18n": "i18next 'app/**/*.js' 'server/**/*.js' && mkdir -p ./build/shared/i18n && cp -R ./shared/i18n/locales ./build/shared/i18n",
     "build:server": "babel -d ./build/server ./server && babel -d ./build/shared ./shared && cp package.json ./build && ln -sf \"$(pwd)/webpack.config.dev.js\" ./build",
     "build:webpack": "webpack --config webpack.config.prod.js",
-    "build": "yarn clean && yarn build:webpack && yarn build:server",
+    "build": "yarn clean && yarn build:webpack && yarn build:i18n && yarn build:server",
     "start": "node ./build/server/index.js",
-    "dev": "nodemon --exec \"yarn build:server && node build/server/index.js\" -e js --ignore build/ --ignore app/",
+    "dev": "nodemon --exec \"yarn build:server && yarn build:i18n && node build/server/index.js\" -e js --ignore build/ --ignore app/",
     "lint": "eslint app server shared",
     "flow": "flow",
     "deploy": "git push heroku master",
@@ -92,6 +93,8 @@
     "fs-extra": "^4.0.2",
     "google-auth-library": "^5.5.1",
     "http-errors": "1.4.0",
+    "i18next": "^19.8.3",
+    "i18next-http-backend": "^1.0.21",
     "immutable": "^3.8.2",
     "imports-loader": "0.6.5",
     "invariant": "^2.2.2",
@@ -137,6 +140,7 @@
     "react-dom": "^16.8.6",
     "react-dropzone": "4.2.1",
     "react-helmet": "^5.2.0",
+    "react-i18next": "^11.7.3",
     "react-keydown": "^1.7.3",
     "react-modal": "^3.1.2",
     "react-portal": "^4.0.0",
@@ -183,6 +187,7 @@
     "fetch-test-server": "^1.1.0",
     "flow-bin": "^0.104.0",
     "html-webpack-plugin": "3.2.0",
+    "i18next-parser": "^3.3.0",
     "jest-cli": "^26.0.0",
     "koa-webpack-dev-middleware": "^1.4.5",
     "koa-webpack-hot-middleware": "^1.0.3",