This is in preparation for making some of Value's members into refcounted ('smart') pointers.
Change-Id: Ibc54e23ac35766a2fd4e14871c9a7c936a603778
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1743
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>