TISTUD-6552 Download and index Node.js core modules for user (for version they have)
  - Fix indexing issue with modules where the properties hanging off the exports global were getting their owning type set to just "exports" and not the name of the module id's exports property type.
  - Add a check for writing a property to index where the owning type doesn't match the type it's actually hanging off of in the model.
  - Implement downloading the node JS source and finding the source in the place where we download it.
  - Fix up CA proposals for things haning off modules. Hack to convert our autogenerated guid for the module to the basename of the module file where it was defined.
  - Add unit tests for NodeJS class
TISTUD-6736 Suggest content assist for string arguments to require function call
  - Quick hack to hook up CA for require call arguments. We ask each require resolver for list of possible module ids in priority order. First one to return a non-null/empty list is what we use for CA.
Add tests for suggesting module ids when we have a node source path and when we don't