dataplane: expose `node_name` and `node_id` in bootstrap response

[boxofrad]

Description

consul-dataplane will support providing either the node_id or node_name in its configuration.

Unfortunately, supporting both in the xDS meta adds a fair amount of complexity (partly because most tables are currently indexed on node_name) so for now we're going to return them both from the bootstrap params endpoint, allowing consul-dataplane to exchange a node_id for a node_name (which it will supply in the xDS meta).