This undoes an accidental breaking change where `prettier.getSupportInfo('1.0.0')` would report supporting the `babel` parser instead of `babylon`.
Fixes#5822
* Implement getSupportInfo() and use it for inference
* Add comment with source of languages.yml
* Fix build, pin semver
* Simplify test snapshots
* Remove stray 'type' property
* Fix parser being overwritten
* Don't infer unreleased parser from extension
* Add CLI and docs for support info