* add circuitv1 protobuf
* add implementation of v1 circuit relay
Intended to be used by standalone daemons and tests
* remove references to go-libp2p-circuit from production code
* update tests to use the in-tree v1 Relay
* use go-log/v2 in relay v1 impl
* use in-tree v1 relay in relay example
* remove go-libp2p-circuit dep from examples go.mod, go mod tidy