feat: verify RpcPath on startup (#2159)

* feat: verify RpcPath on startup

* feat: support http header Grpc-Timeout

gateway/internal/timeout_test.go

@@ -0,0 +1,22 @@
+package internal
+
+import (
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetTimeout(t *testing.T) {
+	req := httptest.NewRequest("GET", "/", nil)
+	req.Header.Set(grpcTimeoutHeader, "1s")
+	timeout := GetTimeout(req.Header, time.Second*5)
+	assert.Equal(t, time.Second, timeout)
+}
+
+func TestGetTimeoutDefault(t *testing.T) {
+	req := httptest.NewRequest("GET", "/", nil)
+	timeout := GetTimeout(req.Header, time.Second*5)
+	assert.Equal(t, time.Second*5, timeout)
+}