chore: import upstream snapshot with attribution

examples/cpp/shared_recording/main.cpp

@@ -0,0 +1,24 @@
+#include <iostream>
+#include <sstream>
+
+#if defined(WIN32)
+#include <process.h>
+#define getpid _getpid
+#else
+#include <unistd.h>
+#endif
+
+#include <rerun.hpp>
+#include <rerun/demo_utils.hpp>
+
+using rerun::demo::grid3d;
+
+int main() {
+    const auto rec =
+        rerun::RecordingStream("rerun_example_shared_recording", "my_shared_recording");
+    rec.spawn().exit_on_failure();
+
+    rec.log("updates", rerun::TextLog(std::string("Hello from ") + std::to_string(getpid())));
+
+    std::cout << "Run me again to append more data to the recording!" << std::endl;
+}