feat: verify RpcPath on startup (#2159)

* feat: verify RpcPath on startup

* feat: support http header Grpc-Timeout

gateway/internal/timeout.go

@@ -0,0 +1,19 @@
+package internal
+
+import (
+	"net/http"
+	"time"
+)
+
+const grpcTimeoutHeader = "Grpc-Timeout"
+
+// GetTimeout returns the timeout from the header, if not set, returns the default timeout.
+func GetTimeout(header http.Header, defaultTimeout time.Duration) time.Duration {
+	if timeout := header.Get(grpcTimeoutHeader); len(timeout) > 0 {
+		if t, err := time.ParseDuration(timeout); err == nil {
+			return t
+		}
+	}
+
+	return defaultTimeout
+}