proxy: add userinfo and webauthn endpoints (#3755)

* proxy: add userinfo and webauthn endpoints

* use TLD for RP id

* use EffectiveTLDPlusOne

* upgrade webauthn

* fix test

* Update internal/handlers/jwks.go

Co-authored-by: bobby <1544881+desimone@users.noreply.github.com>

Co-authored-by: bobby <1544881+desimone@users.noreply.github.com>

internal/handlers/signout.go

@@ -0,0 +1,27 @@
+package handlers
+
+import (
+	"net/http"
+
+	"github.com/pomerium/pomerium/internal/httputil"
+	"github.com/pomerium/pomerium/ui"
+)
+
+// SignOutConfirmData is the data for the SignOutConfirm page.
+type SignOutConfirmData struct {
+	URL string
+}
+
+// ToJSON converts the data into a JSON map.
+func (data SignOutConfirmData) ToJSON() map[string]interface{} {
+	return map[string]interface{}{
+		"url": data.URL,
+	}
+}
+
+// SignOutConfirm returns a handler that renders the sign out confirm page.
+func SignOutConfirm(data SignOutConfirmData) http.Handler {
+	return httputil.HandlerFunc(func(w http.ResponseWriter, r *http.Request) error {
+		return ui.ServePage(w, r, "SignOutConfirm", data.ToJSON())
+	})
+}