This commit adds handling so that the replication stream considers
whether the user intends to peer through mesh gateways.
The subscription will return server or mesh gateway addresses depending
on the mesh configuration setting. These watches can be updated at
runtime by modifying the mesh config entry.
Previously there was a field indicating the operation that triggered a
secrets write. Now there is a message for each operation and it contains
the secret ID being persisted.
Previously the updates to the peering secrets UUID table relied on
inferring what action triggered the update based on a reconciliation
against the existing secrets.
Instead we now explicitly require the operation to be given so that the
inference isn't necessary. This makes the UUID table logic easier to
reason about and fixes some related bugs.
There is also an update so that the peering secrets get handled on
snapshots/restores.
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.