Pass local paths to transformers

Summary:
Pass `localPath` to transformers to allow usage of plugins like `transform-react-jsx-source` that don’t conflict with x-machine caches, e.g. Buck or our own global cache.
These caches don’t work properly if paths local to a specific machine are part of cached outputs.

Reviewed By: jeanlauliac

Differential Revision: D5044147

fbshipit-source-id: 1177afb48d6dd9351738fcd4da8f9f6357e25e81

packager/src/ModuleGraph/worker/transform-module.js

@@ -72,6 +72,7 @@ function transformModule(
   Object.keys(variants).forEach(name => {
     tasks[name] = asyncify(() => transformer.transform({
         filename,
+        localPath: filename,
         options: {...defaultTransformOptions, ...variants[name]},
         src: code,
       })