The forge now creates a human's account on their first authelia login,
so the verb has no job left. Deletes it, HostRequest::ForgeCreateUser,
its handler, provision_user_token, change_user_password and the hive's
TOKEN_SCOPES. change_user_password also passed the password as an
argument to `forgejo admin user change-password`, so it showed in the
container's process list.
ensure_user_exists and mint_token stay for the `core` bootstrap, their
one caller now. ensure_user_exists loses its password parameter: only the
deleted path set one.
Refs #3782
Delete ensure_user_for and mint_and_persist_agent_token, the user step
of sync_agent (the per-rebuild re-mint, #4644) and of
forge_after_first_spawn, and the hive-priv WriteAgentForgeToken request
that wrote the token into the agent's state dir. hivectl forge
create-user now refuses an agent and points at swarmctl agent
mint-forge-token. mint_token, ensure_user_exists and TOKEN_SCOPES stay:
provision_user_token and the core bootstrap still call them.
Refs #3782
