* feat: enable plugin-specific comment functionality
This change enables language plugins to provide their own "handleComment" function. To do so, we're exposing the addLeadingComment, addTrailingComment, and addDangling comment functions which attach comment nodes correctly in the ast which will get handled by prettier core when printing.
* moving js comment functionality to plugin
* Split out location extraction into plugin config
* Reduce set of exported function, rebase to current master
* Pass custom locStart/locEnd fn's directly to affected methods
* (wip) always use locStart/locEnd from plugin
* Convert graphql implementation
* Convert HTML implementation
* (wip) convert JS implementation
* Remove unused variables
* Continue conversion of JS implementation
* Replace "util.locStart" with direct call to "options.locStart"
* Remove util closure
* Add unit test for structure of shared util
* Fix linting error, simplify locStart/End implementations
Evilebot Tnawi