core(minor): Add a way to print out system information for debugging purposes. (#15718)

To use: 

```bash
python -m langchain_core.sys_info
```

libs/core/langchain_core/sys_info.py

@@ -0,0 +1,58 @@
+"""Print information about the system and langchain packages for debugging purposes."""
+from typing import Sequence
+
+
+def print_sys_info(*, additional_pkgs: Sequence[str] = tuple()) -> None:
+    """Print information about the environment for debugging purposes."""
+    import platform
+    import sys
+    from importlib import metadata, util
+
+    packages = [
+        "langchain_core",
+        "langchain",
+        "langchain_community",
+        "langserve",
+    ] + list(additional_pkgs)
+
+    system_info = {
+        "OS": platform.system(),
+        "OS Version": platform.version(),
+        "Python Version": sys.version,
+    }
+    print()
+    print("System Information")
+    print("------------------")
+    print("> OS: ", system_info["OS"])
+    print("> OS Version: ", system_info["OS Version"])
+    print("> Python Version: ", system_info["Python Version"])
+
+    # Print out only langchain packages
+    print()
+    print("Package Information")
+    print("-------------------")
+
+    for pkg in packages:
+        try:
+            found_package = util.find_spec(pkg)
+        except Exception:
+            found_package = None
+        if found_package is None:
+            print(f"> {pkg}: Not Found")
+            continue
+
+        # Package version
+        try:
+            package_version = metadata.version(pkg)
+        except Exception:
+            package_version = None
+
+        # Print package with version
+        if package_version is not None:
+            print(f"> {pkg}: {package_version}")
+        else:
+            print(f"> {pkg}: Found")
+
+
+if __name__ == "__main__":
+    print_sys_info()

libs/core/tests/unit_tests/test_sys_info.py

@@ -0,0 +1,6 @@
+from langchain_core.sys_info import print_sys_info
+
+
+def test_print_sys_info() -> None:
+    """Super simple test to that no exceptions are triggered when calling code."""
+    print_sys_info()