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

pkg/client/client.go

@@ -14,6 +14,7 @@ import (
 	"golang.org/x/oauth2"
 	"gopkg.in/square/go-jose.v2"
 
+	"github.com/zitadel/logging"
 	"github.com/zitadel/oidc/v3/pkg/crypto"
 	httphelper "github.com/zitadel/oidc/v3/pkg/http"
 	"github.com/zitadel/oidc/v3/pkg/oidc"
@@ -37,6 +38,10 @@ func Discover(ctx context.Context, issuer string, httpClient *http.Client, wellK
 	if err != nil {
 		return nil, err
 	}
+	if logger, ok := logging.FromContext(ctx); ok {
+		logger.Debug("discover", "config", discoveryConfig)
+	}
+
 	if discoveryConfig.Issuer != issuer {
 		return nil, oidc.ErrIssuerInvalid
 	}