Remove NIOLockedValueBox from EndpointPath

[Joannis]

It's not needed (anymore) because we expect the entire context setup to be value types

[adam-fowler]

You should run tests before, committing stuff. This is needed at the moment as the router path is resolved after middleware are run in the HummingbirdRouter. So the endpoint needs to be a reference. An alternative optimisation would be to add a protocol

protocol EndpointRequestContext {
    let endpoint: Endpoint
}

and require that the tracing and metrics middleware are only available when the request context conforms to this protocol. They are the only times the endpoint is needed

[Joannis]

Ah I forgot about HummingbirdRouter, sorry!