R1:5d8457a07ee3

In the repository URI index, store Phabricator's own URIs as tokens

Summary:
Fixes T13435. If you move Phabricator or copy data from one environment to another, the repository URI index currently still references the old URI, since it writes the URI as a plain string. This may make "arc which" and similar workflows have difficulty identifying repositories.

Instead, store the "phabricator.base-uri" domain and the "diffusion.ssh-host" domain as tokens, so lookups continue to work correctly even after these…