Convert QueryResults.js to TypeScript

[kfranqueiro]

Convert src/QueryResults.js to TypeScript as src/QueryResults.ts.

In order to run unit tests with the changes, any instances of QueryResults in JS files will need to be changed to QueryResults.default in other modules until we convert them as well.

There is no unit test module dedicated to QueryResults to convert for this task - it is tested via store tests in other modules.

See #130 for general information on the conversion. If you have questions, comments, or thoughts for this module beyond the conversion itself, you can leave comments on this issue.

[kfranqueiro]

Comments for future consideration:

• The QueryResults module still contains various artifacts from before dstore made the jump to always returning promises from most APIs. I suspect that the module could be simplified by taking that into consideration.
• We've traditionally always treated QueryResults like a constructor, but it never actually was one (even in dojo/store). This is awkward any time you actually think about it, and we should maybe consider straightening that out somehow.