Fixes a bug introduced by #15346 where we'd always require an ACL
token even if ACLs were disabled because we were erroneously
treating `nil` identity as anonymous.
Previously, these endpoints required `service:write` permission on _any_
service as a sort of proxy for "is the caller allowed to participate in
the mesh?".
Now, they're called as part of the process of establishing a server
connection by any consumer of the consul-server-connection-manager
library, which will include non-mesh workloads (e.g. Consul KV as a
storage backend for Vault) as well as ancillary components such as
consul-k8s' acl-init process, which likely won't have `service:write`
permission.
So this commit relaxes those requirements to accept *any* valid ACL token
on the following gRPC endpoints:
- `hashicorp.consul.dataplane.DataplaneService/GetSupportedDataplaneFeatures`
- `hashicorp.consul.serverdiscovery.ServerDiscoveryService/WatchServers`
- `hashicorp.consul.connectca.ConnectCAService/WatchRoots`
Previously, public referred to gRPC services that are both exposed on
the dedicated gRPC port and have their definitions in the proto-public
directory (so were considered usable by 3rd parties). Whereas private
referred to services on the multiplexed server port that are only usable
by agents and other servers.
Now, we're splitting these definitions, such that external/internal
refers to the port and public/private refers to whether they can be used
by 3rd parties.
This is necessary because the peering replication API needs to be
exposed on the dedicated port, but is not (yet) suitable for use by 3rd
parties.
Ronald