Supplemental material is available online only.

ACKNOWLEDGMENTS
We thank Christopher Loo and Jeffrey Barnet for their critical readings of the manuscript. We thank Jonah Sacha and Paul Spellman for their helpful discussions.
The contents do not necessarily represent the views of the U.S. Department of Veterans Affairs or the United States Government.
R.F.T. was supported by the U.S. Department of Veterans Affairs under award number 1IK2CX002049-01 and by the Sunlin & Priscilla Chou Foundation.