tokend is responsible for issuing service-scoped tokens based on the token held
and generated by the Vault Agent.
It can also generate "server-user" scoped tokens, which exist for convenience's
sake: they are not a strong attestation of the user on the machine, and have
limited privileges compared to a Vault token issued using e.g. `vault login
-method=oidc`.
This UDS is going to be private to vault-agent and tokend (which doesn't exist
yet).
As a stopgap, for the moment, secretsmgrd will be granted direct access to
speak to the Vault Agent over the UDS.
tokend will be responsible for provisioning applications with tokens, by
issuing subtokens which have roles corresponding to the user account requesting
access.
