CLI should expose fqn-reindex functionality

[jakedoublev]

Background

The platform binary has a command to trigger reindexing of attribute FQNs as they are eventually consistent. Updates to the names of attribute namespaces or definitions and the values of attribute values trigger changes to FQNs, and manual database changes do not trigger the FQNs table to update, so this is a valuable tool for admins who may find themselves with that need.

Platform command: https://github.com/opentdf/platform/blob/main/service/cmd/policy.go#L29

As the CLI UX of the OpenTDF Platform, otdfctl could support this functionality.

Acceptance Criteria

1. The platform command runs on a db connection, but that should not be exposed to clients outside the platform, so an RPC must be added to the policy services.
   1. new protos
   2. new RPC to handle those protos
   3. new integration tests
2. Otdfctl should utilize that new rpc to allow reindexing of FQNs for platform admins