feat: docs i18n support (continuation from #14818) (#17190)

* Initial commit for i18n support

* Bring out index page

* Lint
	modified:   src/pages/index.js

* More Crowdin ephemera

* copy src content to i18n/**/docusaurus-plugin-content-docs/current folders

* run write-translations

* remove superflous files in i18n

* fix formatting

* remove icons folders from translations, add ja, pt, vi translations

* fix formatting

* update translation JSON files

* add crowdin support & crowdin:sync command, sync with crowdin

* exclude failing locales

* remove i18n from git cache, add write-heading-ids script

* add crowdin:sync to before_install.sh script

* add write-i18m shortening script & crowdin:download script (also to before_install.sh)

* move crowdin:download from before_install.sh to prebuild hook

* remove prebuild hook

* remove crowdin script, bump deps

* re-add cli/usage

* update package-lock.json

* add translation sync to build.sh for master

* update README

* add ja to localesNotBuilding, write e-ids

* fix formatting

* get on sync with master

* replace check for master branch

* change build script to work on travis

* use refs instead of names

* fix build.sh

* replace head ref check with channel check

* get stable channel in build.sh

* remove zip

* remove header ids

Co-authored-by: rmshea <8948187+rmshea@users.noreply.github.com>

docs/crowdin.yml

@@ -0,0 +1,16 @@
+project_id: '2'
+api_token_env: 'CROWDIN_PERSONAL_TOKEN'
+base_url: 'https://solana.crowdin.com'
+preserve_hierarchy: true
+files: [
+    # JSON translation files
+    # {
+    # source: '/i18n/en/**/*',
+    # translation: '/i18n/%two_letters_code%/**/%original_file_name%',
+    #},
+    # Docs Markdown files
+    {
+      source: '/src/**/*.md',
+      translation: '/i18n/%two_letters_code%/docusaurus-plugin-content-docs/current/**/%original_file_name%',
+    },
+  ]