chore(tracing): create new rpc call wrapper type with trace info (#443)

Supporting types for #5748, allowing us to pass trace context to Ocaml
with each RPC call.

- [x] I ran `make setup && make` to update the generated code after
editing a `.atd` file
- [x] I made sure we're still backward compatible with old versions of
the CLI.
For example, the Semgrep backend need to still be able to *consume* data
	  generated by Semgrep 1.50.0.
See
https://atd.readthedocs.io/en/latest/atdgen-tutorial.html#smooth-protocol-upgrades
	  Note that the types related to the semgrep-core JSON output or the
	  semgrep-core RPC do not need to be backward compatible!
- [x] Any accompanying changes in `semgrep-proprietary` are approved and
ready to merge once this PR is merged

Author: bkettle

semgrep_output_v1.atd

@@ -3520,6 +3520,13 @@ type function_result = {
   profiling_results: profiling_entry list;
 }
 
+(* Wraps a function_call with the caller's OpenTelemetry span ID for per-request tracing.
+   The trace ID is read from the environment (set by the Python process before starting OCaml). *)
+type rpc_call = {
+  call: function_call;
+  ?parent_span_id: string option;
+}
+
 (*****************************************************************************)
 (* Misc *)
 (*****************************************************************************)