Flight recoder data as JSON (#129505)

Summary:
Provide a new API to retrieve flight recorder data as JSON.
The one minor difference between flight recorder as Pickle v/s JSON is
that the JSON API does not retrieve stack traces at the moment.
This ends up being far too much data.

Test Plan:
unit test

Differential Revision: [D59536460](https://our.internmc.facebook.com/intern/diff/D59536460)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/129505
Approved by: https://github.com/wconstab, https://github.com/d4l3k

torch/csrc/distributed/c10d/init.cpp

@@ -3194,6 +3194,23 @@ such as `dist.all_reduce(tensor, async_op=True)`.
         Arguments:
           tensors(List[torch.Tensor]): List of tensors we want to hash.
       )");
+  module.def(
+      "_dump_nccl_trace_json",
+      [](std::optional<bool> includeCollectives,
+         std::optional<bool> onlyActive) {
+        return py::bytes(::c10d::dump_nccl_trace_json(
+            includeCollectives.value_or(true), onlyActive.value_or(false)));
+      },
+      py::arg("includeCollectives") = std::optional<bool>(),
+      py::arg("onlyActive") = std::optional<bool>(),
+      R"(
+      Arguments:
+            includeCollectives(bool, optional): Whether to include collective work traces. Default is True.
+            onlyActive (bool, optional): Whether to only include active collective work traces. Default is False.
+      Returns:
+            Stringified json work traces.
+            Default settings return everything - i.e. contains NCCL comm dumps and collective traces.
+      )");
   module.def(
       "_dump_nccl_trace",
       [](std::optional<bool> includeCollectives,