Adds a new gRPC endpoint to get envoy bootstrap params. The new consul-dataplane service will use this
endpoint to generate an envoy bootstrap configuration.
Introduces a gRPC endpoint for signing Connect leaf certificates. It's also
the first of the public gRPC endpoints to perform leader-forwarding, so
establishes the pattern of forwarding over the multiplexed internal RPC port.
Adds a new gRPC streaming endpoint (WatchRoots) that dataplane clients will
use to fetch the current list of active Connect CA roots and receive new
lists whenever the roots are rotated.