get rid of ldap and oidc, refactor error handling

Signed-off-by: Jörn Friedrich Dreyer <jfd@butonic.de>

graph/go.mod

@@ -6,12 +6,12 @@ require (
 	contrib.go.opencensus.io/exporter/jaeger v0.2.1
 	contrib.go.opencensus.io/exporter/ocagent v0.7.0
 	contrib.go.opencensus.io/exporter/zipkin v0.1.2
+	github.com/ascarter/requestid v0.0.0-20170313220838-5b76ab3d4aee
 	github.com/asim/go-micro/v3 v3.5.1-0.20210217182006-0f0ace1a44a9
 	github.com/cs3org/go-cs3apis v0.0.0-20210702091910-85a56bfd027f
 	github.com/cs3org/reva v1.10.0
 	github.com/go-chi/chi v4.1.2+incompatible
 	github.com/go-chi/render v1.0.1
-	github.com/go-ldap/ldap/v3 v3.3.0
 	github.com/micro/cli/v2 v2.1.2
 	github.com/oklog/run v1.1.0
 	github.com/openzipkin/zipkin-go v0.2.5