feat(tvix/store/nar-bridge): Setup OpenTelemetry

Sets up OpenTelemetry integration for nar-bridge. Right now it will
export spans for HTTP server requests and all gRPC client requests.
Having the spans available will make performance work significantly
easier as it provides a high level overview of where time is being
spent.

In the future we can add application-specifc metrics and
integrate logrus.

Change-Id: Ie3860675d7ffc626a95673ba062c3c798d8bb2a7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10678
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Autosubmit: Connor Brewster <cbrewster@hey.com>

tvix/nar-bridge/pkg/http/server.go

@@ -12,6 +12,7 @@ import (
 	"github.com/go-chi/chi/middleware"
 	"github.com/go-chi/chi/v5"
 	log "github.com/sirupsen/logrus"
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
 )
 
 type Server struct {
@@ -46,6 +47,9 @@ func New(
 	priority int,
 ) *Server {
 	r := chi.NewRouter()
+	r.Use(func(h http.Handler) http.Handler {
+		return otelhttp.NewHandler(h, "http.request")
+	})
 
 	if enableAccessLog {
 		r.Use(middleware.Logger)