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 08fb61ce36.

* 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>

i18next-parser.config.js

@@ -0,0 +1,84 @@
+// @flow
+module.exports = {
+  contextSeparator: "_",
+  // Key separator used in your translation keys
+
+  createOldCatalogs: false,
+  // Save the \_old files
+
+  defaultNamespace: "translation",
+  // Default namespace used in your i18next config
+
+  defaultValue: "",
+  // Default value to give to empty keys
+
+  indentation: 2,
+  // Indentation of the catalog files
+
+  keepRemoved: false,
+  // Keep keys from the catalog that are no longer in code
+
+  keySeparator: false,
+  // Key separator used in your translation keys
+  // If you want to use plain english keys, separators such as `.` and `:` will conflict. You might want to set `keySeparator: false` and `namespaceSeparator: false`. That way, `t('Status: Loading...')` will not think that there are a namespace and three separator dots for instance.
+
+  // see below for more details
+  lexers: {
+    hbs: ["HandlebarsLexer"],
+    handlebars: ["HandlebarsLexer"],
+
+    htm: ["HTMLLexer"],
+    html: ["HTMLLexer"],
+
+    mjs: ["JavascriptLexer"],
+    js: ["JsxLexer"], // if you're writing jsx inside .js files, change this to JsxLexer
+    ts: ["JavascriptLexer"],
+    jsx: ["JsxLexer"],
+    tsx: ["JsxLexer"],
+
+    default: ["JavascriptLexer"],
+  },
+
+  lineEnding: "auto",
+  // Control the line ending. See options at https://github.com/ryanve/eol
+
+  namespaceSeparator: ":",
+  // Namespace separator used in your translation keys
+  // If you want to use plain english keys, separators such as `.` and `:` will conflict. You might want to set `keySeparator: false` and `namespaceSeparator: false`. That way, `t('Status: Loading...')` will not think that there are a namespace and three separator dots for instance.
+
+  output: "shared/i18n/locales/en_US/translation.json",
+  // Supports $LOCALE and $NAMESPACE injection
+  // Supports JSON (.json) and YAML (.yml) file formats
+  // Where to write the locale files relative to process.cwd()
+
+  input: undefined,
+  // An array of globs that describe where to look for source files
+  // relative to the location of the configuration file
+
+  sort: false,
+  // Whether or not to sort the catalog
+
+  skipDefaultValues: false,
+  // Whether to ignore default values.
+
+  useKeysAsDefaultValue: true,
+  // Whether to use the keys as the default value; ex. "Hello": "Hello", "World": "World"
+  // This option takes precedence over the `defaultValue` and `skipDefaultValues` options
+
+  verbose: false,
+  // Display info about the parsing including some stats
+
+  failOnWarnings: false,
+  // Exit with an exit code of 1 on warnings
+
+  customValueTemplate: null,
+  // If you wish to customize the value output the value as an object, you can set your own format.
+  // ${defaultValue} is the default value you set in your translation function.
+  // Any other custom property will be automatically extracted.
+  //
+  // Example:
+  // {
+  //   message: "${defaultValue}",
+  //   description: "${maxLength}", // t('my-key', {maxLength: 150})
+  // }
+};