This change converts the old `RB.DiffFragmentQueueView` to TypeScript, along with the DataUtils methods which it uses. This involves several pieces: - Changed the queue to not inherit from a Backbone view. This doesn't actually do any view things, it's purely an orchestration class. - Renamed it to `DiffFragmentQueue` and moved into a utils/ directory. - Updated the `DataUtils` methods to return promises for their results, and marked the callback function parameters as deprecated. - Rewrote the fragment loading to use promises and async/await instead of `$.funcQueue`, and `fetch` instead of `$.ajax`. Testing Done: - Ran js-tests. - Opened a review request with a bunch of diff comments and saw all the diff comment fragments load correctly. - Opened the review dialog with a bunch of pending diff comments and saw all the diff comment fragments load correctly. - Expanded sections of the diff for the reviews and review dialogs.