feat: support YAML (#4563)

* feat: support YAML

* fix: do not indent sequence in mappingValue

* docs: add yaml to index.md

* fix: reduce `SyntaxError: Node#parse consumed no characters`

* chore: remove old-build and new-worker.js

* refactor

* refactor

* refactor

* refactor

* refactor

* refactor

* refactor

* refactor

* refactor

* refactor

* refactor

* refactor

* fix: no space after `<<`

* fix: add yaml to standalone test

* test: add tests

* fix: next empty line in flow collection

* fix: tabs are not allowed
http://yaml.org/spec/1.2/spec.html#space/indentation/

* fix: update parser

* feat: rewrite the mappingItem logic
* feat: indent sequence in mapping
* feat(doc): add ifBreak#groupId and group#id

* chore: fix node 4

* chore: add tools_yaml.svg

* chore: remove resolved TODO

* refactor: remove unnecessary workaround

* chore(worker): importScriptOnce

* chore(build): rename with babelPlugins

* make it rollup compatible

* feat: support singleQuote

* refactor

README.md

@@ -15,6 +15,7 @@
   · GraphQL
   · JSON
   · Markdown
+  · YAML
   · <a href="https://prettier.io/docs/en/plugins.html">
       Your favorite language?
     </a>