feat: add slog logging (#432)

* feat(op): user slog for logging

integrate with golang.org/x/exp/slog for logging.
provide a middleware for request scoped logging.

BREAKING CHANGES:

1. OpenIDProvider and sub-interfaces get a Logger()
method to return the configured logger;
2. AuthRequestError now takes the complete Authorizer,
instead of only the encoder. So that it may use its Logger() method.
3. RequestError now takes a Logger as argument.

* use zitadel/logging

* finish op and testing
without middleware for now

* minimum go version 1.19

* update go mod

* log value testing only on go 1.20 or later

* finish the RP and example

* ping logging release

example/server/storage/oidc.go

@@ -3,6 +3,7 @@ package storage
 import (
 	"time"
 
+	"golang.org/x/exp/slog"
 	"golang.org/x/text/language"
 
 	"github.com/zitadel/oidc/v3/pkg/oidc"
@@ -41,6 +42,19 @@ type AuthRequest struct {
 	authTime time.Time
 }
 
+// LogValue allows you to define which fields will be logged.
+// Implements the [slog.LogValuer]
+func (a *AuthRequest) LogValue() slog.Value {
+	return slog.GroupValue(
+		slog.String("id", a.ID),
+		slog.Time("creation_date", a.CreationDate),
+		slog.Any("scopes", a.Scopes),
+		slog.String("response_type", string(a.ResponseType)),
+		slog.String("app_id", a.ApplicationID),
+		slog.String("callback_uri", a.CallbackURI),
+	)
+}
+
 func (a *AuthRequest) GetID() string {
 	return a.ID
 }