Summary:
See PHI604. Ref T13130. Ref T13105. There's currently no way to turn blame off in Diffusion. Add a "Hide Blame" option to the "View Options" dropdown so it can be toggled off.
Also fix a couple of bugs around this: for example, if you loaded a Jupyter notebook and then switched to "Source" view, blame would incorrectly fail to activate because the original rendering of the "stage" used an asynchronous engine so `willRenderRef()` wasn't called to populate blame.
Test Plan:
- Viewed a source file, toggled blame off/on, reloaded page to see state stick in URL.
- Viewed a Jupyter notebook, toggled to "Source" view, saw blame.
- Viewed stuff in Files (no blame UI options).
- Tried to do some invalid stuff like toggle blame on a non-blame engine (options disable properly).
Reviewers: amckinley
Reviewed By: amckinley
Maniphest Tasks: T13130, T13105
Differential Revision: https://secure.phabricator.com/D19414