Move rtc::NewClosure into own build target as ToQueuedTask

to make it usable without need to depend on rtc_task_queue

Bug: webrtc:10191
Change-Id: I2ae1445cf5d498aa6928d66b6823f2f940987767
Reviewed-on: https://webrtc-review.googlesource.com/c/125084
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26942}
diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index 6ebb980..0759fde 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -500,6 +500,7 @@
     ":macromagic",
     "../api/task_queue",
     "system:rtc_export",
+    "task_utils:to_queued_task",
     "//third_party/abseil-cpp/absl/memory",
   ]
 }