createModule working in Windows (#245)

This is the same change as in #243 but for modules.

This gets the createModule tests passing. In theory it also was preventing windows users from creating new modules
(though we currently don't allow anybody to create modules anyways).
With this all of the frontend jest tests are passing!

J=SLAP-2790
TEST=auto

packages/studio/src/store/createModuleAction.ts

@@ -16,7 +16,7 @@ export default function getCreateModuleAction(
   function throwIfInvalidFilepath(filepath: string) {
     const modulesFolder = get().studioConfig.paths.modules;
     const moduleName = path.basename(filepath, ".tsx");
-    if (!path.isAbsolute(filepath) || !filepath.startsWith(modulesFolder)) {
+    if (!filepath.startsWith(modulesFolder)) {
       throw new Error(
         `Error creating module: modulePath is invalid: "${path.relative(
           modulesFolder,