Generated unit test to verify regression and performance

Summary:
This is a preparation diff to address performance issues in the GraphQL plugin, by making sure we can detect functional regressions and measure performance changes.

For reference, current performance impact: `Reducer took 6338ms. to process 42 events` on my machine with this data snapshot (~10sec of recorinding graphQL events on FB4a)

See D18907455 for some background.

Reviewed By: passy

Differential Revision: D18930652

fbshipit-source-id: 58c832f21ae60954bbd7a60c088479aef29ab874

static/compilePlugins.js

@@ -71,6 +71,7 @@ function watchChanges(
         if (
           filename &&
           !filename.startsWith('.') &&
+          !filename.includes('__tests__') &&
           !delayedCompilation[plugin.name]
         ) {
           delayedCompilation[plugin.name] = setTimeout(() => {