Add async completion coordinator

PiperOrigin-RevId: 982070232

Author: l46kok

runtime/planner/BUILD.bazel

@@ -28,3 +28,10 @@ java_library(
     visibility = ["//:internal"],
     exports = ["//runtime/src/main/java/dev/cel/runtime/planner:async_gate"],
 )
+
+java_library(
+    name = "async_completion_coordinator",
+    testonly = 1,
+    visibility = ["//:internal"],
+    exports = ["//runtime/src/main/java/dev/cel/runtime/planner:async_completion_coordinator"],
+)