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>

app/stores/UiStore.js

@@ -9,6 +9,9 @@ import type { Toast } from "types";
 const UI_STORE = "UI_STORE";
 
 class UiStore {
+  // has the user seen the prompt to change the UI language and actioned it
+  @observable languagePromptDismissed: boolean;
+
   // theme represents the users UI preference (defaults to system)
   @observable theme: "light" | "dark" | "system";
 
@@ -47,6 +50,7 @@ class UiStore {
     }
 
     // persisted keys
+    this.languagePromptDismissed = data.languagePromptDismissed;
     this.tocVisible = data.tocVisible;
     this.theme = data.theme || "system";
 
@@ -68,6 +72,11 @@ class UiStore {
     }
   };
 
+  @action
+  setLanguagePromptDismissed = () => {
+    this.languagePromptDismissed = true;
+  };
+
   @action
   setActiveDocument = (document: Document): void => {
     this.activeDocumentId = document.id;
@@ -181,6 +190,7 @@ class UiStore {
   get asJson(): string {
     return JSON.stringify({
       tocVisible: this.tocVisible,
+      languagePromptDismissed: this.languagePromptDismissed,
       theme: this.theme,
     });
   }