Review Board 4.0 introduced a new set of template blocks for setting the

JavaScript page model/view and any attributes or options needed by the

page. This wasn't being used by some of the pages, resulting in a

warning in the debug console.
This change switches over the review request page, diff viewer, and

review UIs to use the modern blocks.
Most of this is pretty mechanical. One change you will notice is that we

are no longer manually injecting the lastActivityTimestamp with a

{% localtime off %} surrounding it. This hasn't actually been needed

in a very long time. Using {% localtime off %} will impact template

filters like |date, which we used to use once upon a time. We've since

moved to using the JSON serializer, which always encodes as UTC, so this

isn't needed anymore. Because of this, this value has simply been moved

into the common page data results that are fed into the model.

Manually tested the review request page, diff viewer, and the image

review UI, making sure they were all working and that the correct state

was getting passed in to the models.
Unit tests pass.